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OsaSync will be discontinued in 2018.
Registering, license extension or subscription renewal is not possible anymore.
Technical support is still available until the end of your subscription period.
OsaSync will continue to run, also after your subscription period has ended.

Our website will be discontinued in May 2018. Our technical support and faq pages will still be available on

We recommend SimpleSYN as an alternative for OsaSync.
It’s cheaper then OsaSync and the company offers a discount of 25% for OsaSync customers. SimpleSYN can be tested 30 days for free.
Use the coupon code OsaSync during the order process (25% off).

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Technical support

Known problems

Please check if you are running the latest version of OsaSync (PRO). If not download our latest version and see if the error comes back. Technical support is only given on the latest version!

How to report an error

Problems while running the OsaSync Connection wizard

The OsaSync connection wizard depends on Windows networking. Windows networking is not always able to browse your network and make connections to your computers on your network. 
General rule of thumb:
If you can browse your network and connect to a network computer using  'Network Neighborhood' or 'My Network Places', OsaSync will also be able to configure a connection to your computer.

Installation / Uninstallation problems

You can also read the Frequently Asked Question on Installation, configuration and  uninstalling.

Errors during synchronization

Other problems

Reporting an error

OsaSync creates log files while running. All errors are also written in these log files. Sending these log files to us is of great help in finding out what went wrong.
The log files are by default recreated each time outlook starts so please make sure to reproduce the problem before sending the files.

Do not restart Outlook before you have send (or copied) the log file(s). You can check if the errors are logged by opening the log file in notepad, it’s just a plain text file.

If you encounter a problem with a contact, appointment or task not being synced as you expected please also refer to the name or subject of this item in your email so it will be possible for us to trace this item in the log files. Make sure the item has been processed on the other computer and send the log files from both computers (also check the log files if the item with this name or subject has been logged before sending. You can open the log files in with Notepad).

Please attach the logfile(s) of both computers to your email when you report an error.
Logfile(s) to attach:

  • for errors while running the OsaSync connection wizard: compname_voswiz.log.

  • for errors encountered during the synchronization process: compname_osasync.log and compname_sync.log

  • for other errors: compname_vosaddin.log and  compname_osasync.log

(compname is replaced by your computer name)

You can access the log files through the logging and errors tab on OsaSync's advanced options page. To access the log files through File Explorer go to the folder  C:\ProgramData\OsaSync . If you don't see the ProgramData  folder then Window's system folders are hidden. To show them, open File Explorer, click File - Options and on the View tab select Show hidden files, folders and drives.

Please also give a brief explanation of what you tried to do when the error occurred.

Report your error with the log files attached to

Make sure to add to your list of trusted senders to prevent our response from ending up in your Junk email folder! Click Actions - Junk email - Junk email options and click Add.

Support by phone

We do not answer questions or give support by phone. This has two major reasons:

  1. We reside in the Netherlands and the time difference makes this quite difficult…

  2. We need to see the log file(s) in order to be able to provide accurate support. Going over a log file by phone is not workable.


If for some reason you are not satisfied with OsaSync then we are happy to refund if your refund request is within the first 6 months after purchasing.

OsaSync menu item has no submenu items or error in clsExplorer.CreateOsaMenu

When Outlook crashes it is possible that Outlook is unable to cleanup the OsaSync menu item while it already removed the OsaSync submenu items.  In this case if you restart Outlook the OsaSync menu in the Outlook main menu bar has no submenu items.
This problem can also result in an error with description 'Method '~' of object '~' failed' in procedure clsExplorer.CreateOsaMenu or in clsMenuWrap.CreateOsaSyncMenu.

To solve this close Outlook and delete the outcmd.dat and extend.dat files in:  C:\Documents and Settings\<user>\Local Settings\Application Data\Microsoft\Outlook).  If you cannot find the files you can use the windows search 'for files or folders' function. Make sure to INCLUDE HIDDEN FILES in your search!

If you are running Outlook 2000 and have not installed the Microsoft Outlook security patch or Office service pack 2 it is possible that Outlook crashes while closing, causing this menu problem. OsaSync uses a third party component to avoid the security dialog but this component may cause Outlook to crash when this security patch isn't installed.
To solve this install the Office 2000  Service Pack 2 or Service Pack 3.

OsaSync doesn't start: the OsaSync menu item is not visible in the Outlook menu

If the Outlook menu doesn't show the OsaSync menu item before the Help menu OsaSync isn't running.

The first reason to rule out is to check if Outlook was already running in the background when you clicked the Outlook icon to start Outlook. If you then click on the Outlook icon to start Outlook then Outlook is simple made visible but is not restarted. OsaSync doesn't start if outlook is started in the background so if Outlook isn't terminated before it's explicitly started by clicking the Outlook icon then OsaSync will not be visible in the Outlook menu.

Check if Outlook was running in the background:

To check this out open the computername_vosaddin.log file that is created by OsaSync each time OsaSync starts. The location of the log file is \documents and settings\all users\application data\OsaSync on Windows XP and \ProgramData\OsaSync on Windows Vista and Windows 7 and 8. Open the vosaddin.log file with notepad and see if the third line displays: ConnectOnConnection: Outlook launched without UI. UI means User Interface so Outlook is started 'invisible'. In this case OsaSync isn't started.

If you don't see the vosaddin.log file then it has not yet been created and this indicates that Outlook has made no attempt to load OsaSync. Proceed with 'Other issues' below to find out why.
If the vosaddin.log file is present and contains errors in the first 20 lines then that is most likely the cause of OsaSync not starting. Send the log file to for help.

Two scenario's that start Outlook in the background are:

  1. You are syncing with a with a PDA or cell phone and you have started your syncing software (like ActiveSync) when Outlook was not running.  This can happen already when a PDA or cell phone is connected. Look on our FAQ page how to prevent this and how to use your PDA together with OsaSync.
  2. You are working in an application like Word or Excel and send an email through this application without opening outlook first. You then start Outlook before you close the application.

If this is the reason why OsaSync is not visible in the Outlook menu then close Outlook and restart Outlook again. If OsaSync is still not visible then Outlook wasn't terminated and is still running in the background so you will have to shut down Outlook explicitly:
Press Ctrl-Alt-Delete to access the Windows Task Manager; click the Processes tab; click the Image Name label to sort all processes and see if Outlook.exe is still running. If so then outlook is still running in the background. Select Outlook.exe and click End process. This will terminate outlook. Do the same with OsaSync.exe if it's there. Then restart Outlook.

Other issues:

If you have ruled out the scenario's above and OsaSync is still not visible then the next thing to check is if OsaSync has been disabled by Outlook. This can happen if Outlook had the impression that OsaSync was misbehaving. Check if OsaSync is listed in the Disabled Items dialog and if so click enable to start OsaSync again and restart Outlook. Here's where to find the Disabled items window:
Outlook 2002/2003: Help - About Microsoft Outlook
Outlook 2007: Help - Disabled items...
Outlook 2010/2013: File - Options - Add-ins (left pane) - drop down list Manage (right pane) - Click on arrow and choose Disabled Items - button Go…

In Outlook 2013 it is possible that Outlook has disabled OsaSync because it considers OsaSync to start too slowly. Go to File - Info and see if below the section Rules and Alerts there is a section Slow and Disabled Add-ins. If so click the Manage Add-ins button and click Always enable this Add-in if OsaSync is listed. If the Slow and Disabled Add-ins section is not visible this indicates that this is not the problem.

If OsaSync has not been disabled by Outlook continue by checking to see if the OsaSync Add-in is selected in the list of installed Add-ins.

Outlook 2000/2002/2003:

  1. From the Outlook menu choose Tools - Options
  2. From tab Other choose Advanced Options...,
  3. Click COM Add-Ins...
  4. See if OsaSync Lite or OsaSync PRO is listed in the list box and has been checked.
  5. If it is listed but is unchecked click the checkbox and click OK, close all windows and restart Outlook.

Outlook 2007:

  1. Outlook 2007: From the Outlook menu choose Tools - Trust Center
  2. In the left pane click Add-Ins
  3. On the bottom of the right pane you see the Manage: box with COM Add-ins selected. Make sure the setting Apply macro security settings to installed add-ins is NOT selected and click Go...
  4. See if OsaSync Lite or OsaSync PRO is listed in the list box and has been checked.
  5. If it is listed but is unchecked click the checkbox and click OK, close all windows and restart Outlook.

Outlook 2010/2013:

  1. Click File - Options
  2. In the left panel click Trust Center
  3. In the right panel click Trust Center Settings
  4. In the left panel click Macro Settings
  5.  Make sure the setting Apply macro security settings to installed add-ins is NOT selected in the right panel and click OK
  6. In the left pane click Add-Ins
  7. On the bottom of the right pane you see the Manage: box with COM Add-ins selected. Click Go...
  8. See if OsaSync PRO is listed in the list box and has been checked.
  9. If it is listed but is unchecked click the checkbox and click OK, close all windows and restart Outlook.

If  OsaSync isn't listed this indicates that OsaSync hasn't been registered properly in Windows.
If the checkmark doesn't work then follow the next steps until the problem is solved:.

  1. Outlook 2002: if you have not installed Microsoft office service packs for Office 2002 then first install the latest service pack from Microsoft. OsaSync does NOT run in the first Outlook 2002 version (!
  2. Outlook 2000 up to Outlook 2010: In the COM Add-Ins list on the COM Add-Ins window, select OsaSyncPro.dll and click Remove. Then choose Add... from this dialogue box and manually select OsaSyncPro.dll in the OsaSync program directory.
  3. When this doesn't work check the value of the following registry key in the Windows registry.
    •  From the Windows start menu, click run and type regedit to start regedit
    • Navigate to the key:
      Outlook 2000 up to Outlook 2010: HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\OsaSyncPro.Connect
      Outlook 2013: HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\Office\Outlook\Addins\OsaSync2013Addin
    • Check if the value of LoadBehaviour is set to 3. If not, double-click on LoadBehaviour and enter 3.
  4. Outlook 2000 up to Outlook 2010: If the OsaSyncPro.Connect key does not exist here's how to create it:
    • Download this small text file. Right-click the link and choose Save Target (or Link) As
    • Rename this file by renaming the file extension .txt to .reg
    • Double-click the file and answer yes to the warning and question.
      The OsaSyncPro.Connect key will now be added.
  5. Outlook 2013: See if all OsaSync files are registered correctly in the Windows Registry:
    • In Windows Explorere navigate to C:\Program Files (x86)\OsaSync 2013
    • Right click the file registerfiles_cs.bat and choose Run as Administrator
    • Several OsaSync files are now registered again in the Windows Registry. For each file a success or error dialog will be shown. If there is an error send an email to and mention the name of the file and the error number.
  6. If this doesn't solve the problem then close Outlook and download and install the latest OsaSync update.
  7. If this doesn't solve the problem then delete the files as explained in OsaSync menu item has no submenu items.
  8. Check your Outlook version number and install the latest Microsoft Office service pack if you haven't done so yet.
  9. Completely uninstall OsaSync. From the windows start menu choose Programs - OsaSync PRO - Uninstall OsaSync PRO. OsaSync will be completely removed from your system. If you follow these steps you don't have to resync folders after reinstallation.
    Now reinstall OsaSync again.
  10. If still unsuccessful then check if you have any other Add-In programs running which might interfere with OsaSync. Look here how to do this.

    Now restart Outlook and see if the OsaSync menu is now showing. If so then you can go back to the Add-In windows and start enabling them one-by-one again. After each enabled Add-In restart Outlook and see if OsaSync is still there. In this way you'll find the Add-In that's interfering with OsaSync.
    For example: a CAD product called 'AutoDesk Survey' causes OsaSync not to be loaded when Outlook starts.
  11. Completely uninstall ALL Add-ins including OsaSync. Now use a registry cleaner utility and clean up the registry (you can google on 'free registry cleaner'). Make sure no reference remains to the file OsaSyncPro.dll and to vaMoreUtils.dll. Then reinstall OsaSync again. If OsaSync works start reinstalling your other Add-ins. After each Add-in installation check if OsaSync still works.
  12. Create a new Outlook profile and delete your current profile by following the steps outlined here.
  13. If this still doesn't solve it then reinstall Outlook. Don't upgrade Outlook from a previous version but do a fresh install.

OsaSync tab is not visible on the folder properties window and neither on the Outlook - Options window.

Somehow the OsaSync component OsaSyncProOCX.ocx (or  vaitaoptionsocx.ocx for OsaSync Lite) hasn't been registered properly in the windows registry. This is why both tab pages can't be displayed. You can manually register this component by typing from the commandline:
"c:\program files\OsaSync\osasyncproocx.ocx" (replace the pathnames with yours if they are different)

If this still doesn't solve it reinstall OsaSync.

OsaSync does not seam to work anymore

First check to see if OsaSync is still running when Outlook is started. If the Outlook menu doesn't show the OsaSync menu item between the Tools and Actions menu items then OsaSync is not running anymore. Follow these guidelines to get OsaSync running again.

Check if all computers do 'see' each other. The OsaSync Options window should list all other computers. If a computer is missing rerun the OsaSync connection wizard again on the missing computer. When configuring in peer-to-peer mode make sure that both computers are looking at the same OsaSync_data folder. If a computer is listed twice see here how to get rid of one instance.

Now resynchronize each folder by running the OsaSync folder resync wizard.

When a folder is resynced but OsaSync still doesn't reflect changes then follow these steps. If necessary create a test item and send us the vosaddin.log files and osasync.log files from BOTH computers. Please mention the NAME or SUBJECT of the test item so we will know what to look for in the log files.

Instead of following the above steps you can also uninstall the current OsaSync installation and start all over again by reinstalling our latest version. Follow the instructions on our getting started page to install, configure and sync folders again.

How to check if other Add-ins are interfering with OsaSync

It is possible that problems arise if several Outlook Add-ins are running that interact intensively with Outlook. It's very hard to say if and when those problems could arise and it's even harder to solve them because there's no way for us or other Add-in authors to see how Outlook handles this interaction.

Unfortunately in certain configurations (Outlook/Windows/OsaSync) it is possible that Outlook sometimes decides to disable OsaSync because it gets the impression that OsaSync is 'misbehaving' although OsaSync is still running fine. This can be due to a problem resulting from the interaction between multiple Add-ins.

In order to rule out any possible interference of other Outlook Add-ins it's best to temporarily disable all other Add-ins in order to see if that solves the OsaSync problems. Here's how:

 Outlook 2007:

  1. From the Outlook menu choose Tools - Trust Center
  2. In the left pane click Add-Ins
  3. On the bottom of the right pane you see the Manage: box with COM Add-ins selected. Make user the setting Apply macro security settings to installed add-ins is NOT selected and click Go...

Outlook 2010/2013/2016:

  1. Click File - Options
  2. In the left panel click Trust Center
  3. In the right panel click Trust Center Settings
  4. In the left panel click Macro Settings
  5.  Make sure the setting Apply macro security settings to installed add-ins is NOT selected in the right panel and click OK
  6. In the left pane click Add-Ins
  7. On the bottom of the right pane you see the Manage: box with COM Add-ins selected. Click Go...

Outlook 2007/2010/2013/2016 continue:

  1. Disable all other Add-Ins other then OsaSync Pro and click OK.
  2. Go to the Trust Center Add-Ins dialog again by again clicking Tools - Trust Center, Add-Ins
  3. In the Manage box click the down-arrow and select Exchange Client Extensions
  4. Disable all other Add-Ins other then OsaSync Pro and click OK.

Earlier Outlook versions:

  1. Go to Outlook's advanced options window: Tools - Options - Other - Advanced Options.... 
  2. See which Add-In programs are listed by clicking the button COM Add-Ins....
  3. Disable all other Add-Ins other then OsaSync Pro.
  4. Click OK to return to the Advanced Options.
  5. Click the button Add-In Manager... to see other Add-In programs and disable everything.

Now continue to use OsaSync in order to see if the problems are solved. If so start enabling the Add-ins again one by one in order to find the Add-in that is causing the trouble. If you find the Add-in that is the source of the OsaSync trouble then uninstall that Add-in and reinstall it again. If the reinstallation does not fix the interference problem also reinstall OsaSync (look here how to completely reinstall OsaSync without the need to resync or reconfigure anything).  If this doesn't help then the only option is to decide which Add-in you are going to discard.

If this didn't help you can take a more drastic approach:

Completely uninstall ALL Add-ins including OsaSync. Now use a registry cleaner utility and clean the Windows registry (you can google on 'free registry cleaner'). Make sure no references remains to the file OsaSyncPro.dll and to vaMoreUtils.dll. Then reinstall OsaSync again. If OsaSync works without problems start reinstalling your other Add-ins. After each Add-in installation check if OsaSync still works.

Some add-ins that were reported to us as causing trouble for osasync are :
- AVG Addin for Outlook
- update of 2011 Windows Life Essential
- update of McAfee Addin
- update of Avast anit-virus

How to run the Outlook repair procedure

Run Detect and Repair from the Outlook Help menu.

In Outlook 2007: Detect and Repair is called Office Diagnostics.

In Outlook 2010, 2013 and 2016: Office diagnostics is no longer available but you can repair Outlook from the Control Panel. In Control panel select Programs and features, select Microsoft Office. Click Change above the file list and choose (Quick) Repair in the installation window.

Computers are listed double on the options page in the list of configured computers

If you have 3 OsaSynced computers COMPUTER_A; COMPUTER_B and COMPUTER_C then the list of configured computers on the OsaSync options page on COMPUTER_A should list COMPUTER_B and COMPUTER_C but now it lists COMPUTER_C twice.

OsaSync stores the configuration information for other computers to sync with in the windows registry and for some reason two registry keys have been created for COMPUTER_C . This can be solved by manually by deleting one registry key:

From the Windows start menu, click run and type regedit to start the windows registry editor regedit. Now navigate to the key HKEY_CURRENT_USER\Software\OsaSync. The sub keys (with names starting from P0001 in peer-to-peer mode or L0001 in C/S mode) correspond to your computers. You can see which computer a key corresponds to by selecting the key and looking at the MachineName value. If there is still a sub key with a computer name instead of P000x or L000x then the conversion process (which ran after installation of version 5.3 or higher) went wrong so then you should delete this key. Otherwise look for the key corresponding to the double computer and press Delete. Then click Ok to confirm and close regedit.

Also see: OsaSync says I have 3 computers but I only have 2

OsaSync says I have 3 computers but I only have 2 and switched to an evaluation version

OsaSync checks if the number of configured computers corresponds to your license version. If OsaSync sees that more computers are configured then allowed by your license type then it switches to being unregistered. If you have not intentionally added a computer without extending your OsaSync license then one of the following scenario's can apply:

  • You have changed a computer but have not yet removed the configuration information for the removed computer.
    See here how to remove the configuration info for the obsolete computer.
  • You have converted OsaSync from an older version but something went wrong and a computer is now listed twice in the OsaSync options window:
    See here how to solve that.

Duplicate items after running the compare folder process

The compare folder process (OsaSync Advanced Options; Exceptional procedures, button compare folder) can result in duplicate in duplicates items:

If you start comparing a folder from computer A (lets say the contacts folder) and computer A does NOT have a contact X while computers B, C and D DO have this contact X. When the compare data created by computer A has been processed on B, C and D then all computers will have 3 instances of this contact X! This is not a bug but a result of how the compare process in OsaSync operates (when computer B imports the contact from A it's not aware of the contacts of C and D).

You can however prevent this from happening by resynchronizing the folder instead of using the folder compare process. When a folder is resynced duplicates will be automatically deleted by OsaSync.

How to get rid of duplicate items

If the Prepare folder for synchronization process has just finished and there are duplicate items in the folder then simply click Check for changes on other computers again. OsaSync needs to process the changes from other computers at least two times before the folder synchronization process is completely finished.

If a folder has duplicate items for other reasons then:

  1. Resynchronize the folder by running the resynchronization wizard. Click: OsaSync - Synced folder - Resynchronize...

  2. On Remove duplicate items step have OsaSync remove duplicate items

  3. Finish the wizard

  4. Have all other computers Check for changes on other computers. OsaSync will delete all duplicate items that were found on the other computer.

  5. Click check for changes on other computers again on all computers.

If OsaSync is ready processing all changes then the number of items on all computers should be the same again.

If you did choose merge folder in the resyncing wizard instead of having OsaSync delete the folder contents prior to syncing then it is possible that when the resyncing process has finished that there are again duplicate items in the folder. This due to the fact that identical items already existed on other computers and have now been copied by the merge process to all synced computers.
To finally get rid of all duplicates run the remove duplicate items procedure: in the OsaSync menu click Options - Advanced options - Exceptional procedures tab and click the button Remove duplicate items. Select the folder and click the Remove duplicates items button. Do this only on one computer; OsaSync will delete the duplicates found on the other computers.

See also:

Calendar contains duplicate birthdays

It is possible that birthdays or anniversaries have become duplicated in the calendar folder.

If you set a contact's birthday or anniversary then Outlook creates the corresponding appointment in the calendar. When OsaSync has synced the contact's changes then Outlook on the synced computers also creates a birthday appointment. Now there is a birthday on each computer but these birthdays are not created by OsaSync so for OsaSync these are different appointments. When a birthday appointment is changed then this change can't be synced.

In order to prevent this and to make sure that a birthday on each computer is properly synced, OsaSync uses a mechanism to restore the connection between the birthdays on each computer. When the birthday date in the contact is changed or set to none then OsaSync changes the birthday appointment accordingly on all computers. Because the complexity of this mechanism sometimes duplicate birthdays can occur.

To clear the calendar of duplicate birthdays and anniversaries:

  • Select the Calendar folder and run the folder resynchronization wizard (OsaSync - Synced folder - Resynchronize...)
  • Click the 'remove duplicates' button on the remove duplicates items step.
  • Finish the wizard and have all other computers check for changes
  • The synchronization process requires a back-and fort communication between computers a few times so click 'check for changes' again on each computer a few times (or wait a while if OsaSync checks automatically)
  • On the computer that ran the resync wizard: run the 'remove duplicate items' procedure again, this time from the OsaSync Advanced options page, tab Exceptional procedures.

The Read/Unread status doesn't sync

Unfortunately the syncing of the Read/Unread status of emails is not consistent. It's very hard for OsaSync to 'catch' the changing of this status and to sync it correctly. We hope to be able to improve this in a future version.

The category applied to an appointment or contact item doesn't sync

OsaSync syncs the category if you apply a category to an Outlook item. However, the applied category should not be a one-character category like category 'A'. A category name should have a length of at least 2 characters

OsaSync question: SKIP or DELETE importing changes; what this?

OsaSync is importing changes from other computers and pops up the following question:

OsaSync is trying to import an item from another computer for synchronization but cannot find the top level Outlook folder 'folder name' and asks if you want to
- SKIP importing changes
- DELETE all import files

This message indicates that OsaSync has received messages from another computer to import changes in the pst file with the top level folder indicated in the message but cannot do so because this pst file is not open in Outlook. When OsaSync is used when multiple top level folders (= multiple pst/ost files) are open in Outlook, than the names of these top level folders have to be the same on the other computers. Otherwise OsaSync doesn’t know in which top level folder a new synced folder has to be created. If there is only one pst file used then off course this issue isn’t there so than the top level folder name can be different than on the other computers.

Makes sure the top level folder names in Outlook are the same on all computers or only use one top level folder. See here how top level folder names can be changed.

Also see:

'Personal Folders' is listed twice in the Outlook folder list

If you have 2 top level folders Personal Folders in the Outlook folder list that refer to the same pst file then OsaSync won’t work properly.

Normally, you can easily add, rename or delete top level folders with Data File Management (tab Data files in Account settings) . However,
getting rid of a second top level folder reference to the same 'Personal Folders' is almost impossible because the Personal Folders .pst file usually is the default .pst file.

If Data File Management does help you will have to create a new Outlook profile

How to create a new Outlook profile

Outlook uses profile information.Outlook profiles can be used to run Outlook with different configurations and are part of the Windows operating system. If you have never created profiles yourself then the default profile 'Outlook' is used.

A profile is a collection of email accounts, data files (= .pst files) and email rules so you will have to recreate the email accounts and have to POINT to the EXISTING pst files again. So you just tell windows again with pst files you want to use with the new profile. These are the same pst files you are using already so you don't create new files and don't lose anything. You don't have to resync or reconfigure anything else either. Recreating the email accounts does take some time but specifying the pst files you can do in a few seconds.

Before creation of a new profile first export your existing email rules if you use any. Start Outlook with the old profile. Then in the Outlook menu click Tools - Rules and alerts. In the Rules and alerts window click Options and Export Rules.

Here's how to create a new Outlook profile:

  1. Close Outlook
  2. Click Start - Settings - Control panel - Mail.
  3. Click Show Profiles.
  4. Click Add and fill out a new profile name.
  5. Choose Add a new mail account and follow the necessary steps by clicking Next. This will set up your email account again.
  6. Select Prompt for a profile to be used and click OK.
  7. A new pst file will be created: outlook1.pst
  8. Start Outlook and choose the new profile.
  9. You will now see a top level folder Personal Folders in the folder list but this Personal Folders refers to the new pst file Outlook1.pst. Give this top level folder a new name:
  10. Right-click Personal Folders and choose Properties for "Personal Folders"...
  11. Click Advanced...
  12. In the Name box fill out a new name like "Test". Click OK twice to close the windows.
  13. We are now going to add your default Personal Folders file. Click File - Open - Outlook Data File...
  14. Select your default pst file outlook.pst and click OK. Your folder list will now list two top level folders: Test and Personal Folders.
  15. Click Tools - Email accounts - View or change existing e-mail accounts and click Next.
  16. In the Deliver new e-mail to the following location box change the standard delivery location to Personal Folders.
  17. Restart Outlook again.
  18. Now you can remove the Test top level folder: right-click on "Test" and choose Close.
  19. Close Outlook.
  20. Now instruct Outlook to always use this new profile when Outlook starts. Repeat steps 2 and 3.
  21. Click Always use this profile and select the new profile name. Click OK.

Now start Outlook with the new profile and import your mail rules again. In the Rules and alerts window click Options again and click Import Rules... and select the export file.

2 more tips:
- You can remove the old profile in the Profiles windows when you are sure everything works fine again.
- When the new profile is complete and ok make a copy so you'll have a valid profile in case something goes wrong in the future. Go to the Profile window (Start - Settings - Control panel - Mail - Show Profiles), select the new profile, click Copy... and fill out a new name.

Error 91 or #995 while OsaSync is starting

Two possible reasons:

  1. This error is caused by a top level folder that is different from a standard Outlook top level folder and is not supported by OsaSync. Top level folders that are different are:
    - top level folders from HTTP accounts like HOTMAIL and MSN
    Microsoft's Business Contact Manager (not supported by OsaSync)
    - WinFax Fax Logs or another top level folder from a fax program
    - Microsoft Exchange Public folders
    When Outlook is started OsaSync iterates all folders and when it tries to iterate this top-level folder it fails.

    You can have OsaSync skip the top level folder by excluding the folder:
    - Choose OsaSync - Options and click the button Advanced Options
    In the Top level folders to exclude for OsaSync section click the button Select folder...
    - select the top level folder to exclude.
  2. Another reason for the error OsaAddIn Run-time error ‘91’:  Object variable or With block variable not set is:
    You are trying to run OsaSync as a logged on user without Administrator rights and the this user doesn't have Write access rights in the folder C:\ProgramData\OsaSync on Windows Visa (\documents and settings\all users\application data\OsaSync on Windows XP).

    To solve this logon again as an Administrator. Select the \ProgramData\OsaSync folder, right click it and select the security tab on the Properties window. Select Users in the upper list and click Write in the Permissions for Users list.

Outlook 'freezes' during the import process of synchronized contacts

Outlook freezes and stops responding when a large number of contacts is imported after having been prepared for synchronization on the other computer. A restart of Outlook is necessary.

For some mysterious reason freezing of Outlook can happen in some configuration combinations of Windows, Outlook and OsaSync. It's also possible that Outlook doesn't freeze but gives 'out of memory' error messages constantly.

If it does happen here are the things to try:

  • Make sure to install the latest Office Service Pack. Especially the first version of Outlook 2002 is known to be less stable. It is also wise to install the latest Windows Service Pack.
  • If freezing happens during the import of outlook items during the synchronization process of a folder with many items you can:
    - Resync this folder. Make sure Outlook is not running on the target computer.
    - The sync preparation process creates .txt (and possibly also .msg and .rtf) files in the folder \OsaSync_Data\computername (computername is the name of the target computer you are syncing to) on the source computer or in client-server mode on the server in the \OsaServer\computername1\computername2  folder. A large folder results in many files. Keep about 500 files in this folder and move the rest to a temporary folder.
    - Start Outlook on the target computer and have OsaSync import the sync files.
    - If all files in the computername folder are gone move around 500 files from your temporary folder back into this folder.
    - Make sure the target computer imports (and deletes) the files and repeat this moving of files until all files are imported.
    This can be a lot of work if you have many items but it only has to be done once.

After synchronizing I see 290 contacts while there are 300 on the other computer

After you have synchronized a contacts folder containing for example 300 items it is possible you see only 290 items on your target computer.

Two reasons for skipping an item are:

  1. Items marked as Private are skipped if the setting Do NOT sync contacts marked as private on the Contact options tab is checked (OsaSync - OsaSync Options - OsaSync Advanced Options - Outlook Item Options - Contacts).  Items are marked private by the check mark in the right corner below on the inspector (=contact edit) window.
  2. Distribution lists (or other non-contact items) in the contacts folder are skipped. Distribution lists are not synced by OsaSync Lite. OsaSync PRO does sync distribution lists..

During the creation of synchronization data and during the importing of this data on the other computer OsaSync writes the results to the logfile computername_sync.log, computername is replaced by the name of your computer. You can review this file on both computers to see what happened.

Open the computername_sync.log file (using notepad) on the computer you started the 'prepare data for synchronization' and browse to the end of the file (all data in this file is appended each time to sync a folder). If the creation of the sync data was successful you will see some lines like these:
READY creating data for items in folder contacts 6-9-2002 11:53:10
Distribution list item skipped  6-9-2002 11:53:10
Number of items skipped because marked as private: 9  6-9-2002 11:53:10
Total items in folder: 300 NO data creation failures! 10 items skipped! 6-9-2002 11:53:10

The last line indicates there are 300 items in the folder but 10 items have been skipped, one item because it is a distribution list and 9 items because they are marked as private (note: older OsaSync versions do not include the private items in the total number of items skipped..)

Now open the computername_sync.log file on your target computer, browse to the end and look for the lines that summaries the import of sync data for the folder you have just synced.
The successful import of the sync data looks like:
START Importing sync data from computer VAITA in folder: contacts 06-09-2002 12:28:29
READY Importing sync data in folder: contacts 06-09-2002 12:29:08
290 items received for this folder from computer VAITA 06-09-2002 12:29:08
290 items imported successfully, NO items failed during importing. 06-09-2002 12:29:08

Here you see that all items received are imported successfully.

If you are sure the number of items you see in the folder is different from the number of successfully imported items indicated in the sync.log file it is best to run the Inbox Repair Tool. It there are invalid or corrupted items in the folder this tool is likely to remove them. If the number of items is till different after you have done this then it's best to resynchronize the folder by running the Resynchronization wizard.

See The sync.log file indicates errors during importing sync data if the sync.log file reports errors.

After synchronization I have folders with duplicate items

Click Check for changes on other computers again. OsaSync will now finish the sync process and delete all duplicate items.

If there are still duplicate items in the folder after OsaSync has checked for changes on other computers at least twice, then you can remove these duplicates by running the Remove duplicate items procedure.

The sync.log file indicates errors during importing sync data

If during the process of importing data files created by your other computer (after having synchronized a folder) something goes wrong an entry will be written to the logfile computername_sync.log. (computername is replaced by your computer name. See above for the location of the logs files)

This entry will look like:
START Importing sync data from computer VAITA in folder: contacts
Error during processing of file \\vaita\C_share\\Data\OsaSync_Data\LAPTOP\000008.txt
Header: SYNCNT#$SYN#$Vaita_000120#%Rons mail0#$Test0#$contacts2
Error nr: 9: Subscript out of range
READY Importing sync data in folder: contacts
40 items received for this folder from computer VAITA
39 items imported successfully, 1 items failed during importing.

If you can't figure out what is wrong or you see an explicit error like in the example above then you can ask for technical support by email (note: you need to have a valid subscription to updates and technical support). Attach the sync.log file, the vosaddin.log file and the osasync.log file. Click here for the location of the log files.

After the problems have been solved it might be necessary to rerun the prepare folder for synchronization process again. See here how to do this.

After synchronization a folder still doesn't match; how to resync a folder

If the initial synchronization process was not successful then retry the preparation of folder synchronization data.

  • If you are not running the latest OsaSync version install the latest version.
  • Resync the folder by running the folder resynchronization wizard. You can run this wizard on any computer but best is to run the resync wizard on the computer that has the the highest number of items in the folder.  Select the folder and click: OsaSync - Synced folder - Resynchronize...
    - If you are sure that the folder on this computer contains ALL items then select EMPTY folder on target computer prior to import. Otherwise select MERGE folder
    - Instruct the wizard to have OsaSync create a new OsaSync folder ID
    - Make sure to select ALL other previously synced computers
    - If the wizard finds a lot of unprocessed files you will be prompted to delete those files. These files probably remain from a previous unsuccessful sync attempt so have the wizard delete those files.
    - If the folder has duplicate items you can remove them in the Remove duplicate items step.

    If the resync wizard cannot be accessed because the OsaSync - Synced folder menu remains grey then the folder is not yet marked for synchronization. Either run the resync wizard on another computer or run the initial Prepare folders for synchronization... wizard.
  • Click check for changes on other computers on the target computers. OsaSync imports the sync data and copies all new items found to all other computers (if you selected merge in the resync wizard).
    If OsaSync could not connect to a computer see here what to do.
  • Click check for changes on other computers again on the computer on which you ran the resync wizard. Items found on other computers are imported and duplicate items are deleted.

If the Summary step of the synchronization wizard indicated errors then read here how to proceed.

If after resyncing there are duplicates items then please read After synchronization I have folders with duplicate items.

Outlook 2002 'freezing' and not responding anymore

see Outlook 2002 'freezes' during the import process of synchronized contacts

OsaSync running slowly; checking for changes takes a long time

Problem: when OsaSync checks for changes on other computers this takes a long time.

Large outlook folders sync slowly only during the prepare folders for syncing procedure (unless synced in advanced mode). However that's a one-time only operation. Also the size of the pst file is no issue. Thereafter only the changes are synced and that should not take much time.

There are however two scenario's that can cause OsaSync to check for changes slowly:

1. There are many OsaSync files that are not deleted and are processed every time when OsaSync checks for changes. This can happen when a previous prepare folders for syncing process did not complete correctly. Another reason for undeleted files is if many items have been moved to another folder and OsaSync could not find these items. The files are not deleted immediately because some syncing scenarios require OsaSync to wait until info from other computers has been received (e.g.: computer A has send an OsaSync message to move an email to another folder but this email has not been received yet from computer B).

This slowness should only be temporary because after a few times OsaSync will delete the files. If for some reason that doesn't happen then you can delete those files yourself. Click Check for changes on other computers and after OsaSync has finished delete all remaining files in the OsaSync data folder:
- in client-server mode (on computer_A): \\server\share\OsaServer\computer_A\computer_B
- in peer-to-peer mode (on computer_A): \\computer_B\OsaSync_Data\computer_A 

2. In peer-to-peer mode:

Whenever OsaSync checks for changes on a computer that is not online then this causes a noticeably delay due to the (lack of) responsiveness of the network. If several computers are offline then this can slow down OsaSync considerably. To prevent OsaSync from trying to connect to offline computers each time when OsaSync checks for changes click the setting If connecting to a computer is not possible STOP TRYING after two attempts on the OsaSync advanced options page.

Also when OsaSync doesn't check for changes a noticeable decrease in Outlook's responsiveness can be experienced from time to time. This can happens when:

  • You have moved or deleted many emails at once. OsaSync will be busy creating sync data for all moved or deleted emails

  • Every hour OsaSync inspects all folders to see if anything has changed. During this check some menu items (like 'checking for changes on other computers') in the OsaSync menu are greyed out

About the performance of the compare process

There has been a major change in the way OsaSync creates and processes compare data. All data used to be created in one go. This resulted in Outlook becoming unusable when this process was running and could lead to outlook freezing up in some cases. Both the creation and actual comparing of data is now done one item at a time. In between two items Outlook regains control. This results in Outlook responding normally to user actions so the user can continue working while the compare process runs. The total amount of time needed for the process has increased of course but this should not be a problem because Outlook keeps responding during this process.
You can experiment a little with the amount of time OsaSync uses before processing another item. If you increase the time Outlook will become more responsive and the total time for the compare process will become longer. To do this increase  the registry value 'CreateCmpDataInterval' in HKEY_CURRENT_USER\Software\OsaSync. This is the interval between creation of compare data for two items (defaults to 250 milliseconds = 1/4 second).  Increase the value 'CompareInterval' to change the time in between the actual comparing of items (defaults to 250 milliseconds = 1/4 second).
The value to set in those keys depends on the speed of your PC. Try for example 10000 (10 seconds) if you don't notice any difference when increasing the values.

Installation error: source file is corrupt

During the installation of OsaSync a message can be shown saying that the source file is corrupt. This is the OsaSyncPRO.dll but can also be another file.

You probably have anti-virus and firewall software running. For some reason this software interferes with the download. Disable both the anti-virus software and the firewall and download OsaSync again.
This problem has been reported with Norton anti-virus and personal firewall.

Error 86 or 1245 in ctlMachines.DoActions

Occurs when clicking the 'Next' button in the wizard step 'Connecting'.
Windows cannot browse your network because of an authentication problem. Your username and/or password are incorrect. This can be the case in Windows 95/98/ME when you skip the login dialog. 
Use 'Network Neighborhood' or 'My Network Places' and try to browse your network. If Windows is unable to browse the network then logoff from the current windows session or restart your computer. Login to Windows again with your username and password.

Licence key does not work

Please make sure to copy and paste the licence key you received in the email into the edit box on the registration page without accidentally adding extra characters (select the key in the email and press Control-C to copy; then in the box on OsaSync registration window click Control-V).

If OsaSync does not recognize the licence key please check if the name of the your computer matches  exactly with the name you provided during the registration process (although not case sensitive). You can check your computer name via control panel - system -  tab network identification.
If your computer name is different from the one specified during the registration process then you can change the computer name for the license key yourself and get a new license key automatically when you login at: Login with your user name and password which you find in the same email as the licence key.

If you are sure the computer name is not the issue then please paste the licence key again on the registration window and send us the computername_vosaddin.log file and osasync.log file before you restart outlook. That enables us to see what goes on.

Restored data from a backup file is not synced

Restored data is recognized by OsaSync if the item has no OsaSync ID or if the last modification time is more recent then the previous time OsaSync checked the folder for changes. Unfortunately Outlook doesn’t update the modification time when an item is moved or copied into a folder. If there are only a few items one can manually open each item, make a dummy change by adding a space to a property and save it. With more items it’s better run the procedure to remove OsaSync ID’s in the backup folder (from the ‘Exceptional procedures’ tab on the OsaSync advanced Options window).  Then copy the items to the actual folder, they will now be seen as newly added items.

Unable to register DLL/OCX: Load Library Failed, code 11 for VaMoreUtils.dll.

If for some reason this error occurs it is best to re-register the OsaSync files in the Windows registry. Open Windows explorer and locate the file
C:\program files\OsaSync\registerfiles.bat (Outlook prior to Outlook 2013)
C:\program files (x86)\OsaSync2013\registerfiles_cs.bat (Outlook 2013)
On Windows Vista, Windows 7 and Windows 8 you have to run this file with administrator rights: right-click on the file and choose Run as administrator.

When running Outlook 2013 you will receive succes or failure messages for each registered osasync file.
For Outlook versions up to Outlook 2010: open the file register_feedback.txt if that file has been created. In this file you will see a succes or failure message for each registered osasync file.

Error on startup: Writing of an entry in the errorlog file has failed.

OsaSync is unable to write to the log files. Those files are in C:\ProgramData\OsaSync. First check if you can create, modify and delete a file manually in this folder (using the user account that runs OsaSync). If not, you have to grant this user full access to this folder. Otherwise, carefully inspect your anti-virus software (update?) and any other security related software because some other application prevents OsaSync from writing to the log files. Disable the other software to find out which application is doing this. Then when you have found out add OsaSync as an exception with full access to the local network. If that doesn’t help or you cannot find out how to add an exception please reinstall that application.

If you want to reinstall OsaSync again note that you may need to manually remove two folders after uninstalling, or else your reinstall will likely fail: C:\Program Files (x86)\OsaSync (or OsaSync2013) and C:\ProgramData\OsaSync. Now you are ready to reinstall.

DllregisterServer failed with error code 0×80004005 during installation

You need to have administrator privileges and rights to install OsaSync and this error indicates that this is not the case.


  • In windows explorer go to the folder where OsaSync has been installed. By default:  C:\Program Files\OsaSync
  • Right-click the file Registerfiles.bat and select Run as administrator

All OsaSync files will now be registered in Windows.

Outlook 2013

Unfortunately on some computers running Outlook 2013 registering OsaSync as administrator still fails. We are still trying to find a solution but have not found one yet.

Connection wizard tells me I have to run as administrator but I already am the administrator

There are two problem sources that can result in this message:

  1. The system does need administrative rights to run the connection wizard
  2. The connection wizard is unable to start another osasync program.


  1. First you should try to run the connection wizard with administrative rights:
    Right-click the file StartConnWizPro.exe in the OsaSync installation folder (default is C:\Program Files\OsaSync). Select Run as administrator.

    If this is indeed the problem then it is also possible to start the OsaSync connection wizard from the OsaSync options window in Outlook (Outlook menu - OsaSync - Options..., button Run connection wizard...). Then this error won’t happen and you are able to configure the computer.
  2. The message that you should run as administrator is incorrect because there is another problem:
    The connection wizard program is a very small program that tries to start code in another osasync program called osasync.exe but fails.

    To find out if this is indeed the problem source start Outlook. Now also the osasync program that runs inside outlook want to start the osasync.exe program. If this fails you will get error number 48 or 429.
    Here's how to solve this problem: Error 48 in proc: clsAImanager.Start. OsaSync menu stays greyed out.

The message interface has returned an unknown error or Method '~' of object '~' failed

If you encounter one of these errors:

  • The message interface has returned an unknown error. If the problem persists please restart Outlook.
  • The error message second part mentions: 'Method '~' of object '~' failed'.

Re-register the OsaSync files in the Windows registry:

Open Windows explorer and locate the file
C:\program files\OsaSync\registerfiles.bat (Outlook prior to Outlook 2013)
C:\program files (x86)\OsaSync2013\registerfiles_cs.bat (Outlook 2013)
On Windows Vista, Windows 7 and Windows 8 you have to run this file with administrator rights: right-click on the file and choose Run as administrator.

When running Outlook 2013 you will receive succes or failure messages for each registered osasync file.
For Outlook versions up to Outlook 2010: open the file register_feedback.txt if that file has been created. In this file you will see a succes or failure message for each registered osasync file.

If this doesn't help then:

  • Empty your deleted items folder. Set outlook to empty the deleted items folder upon exiting (Tools - Options - Other - Empty the Deleted Items folder upon exiting)
  • Run the Outlook repair procedure
  • Run the Inbox Repair Tool.

If none of the above actions fixes the problem there is one last drastic action you can take :

  • Backup you .pst file
  • Remove all OsaSync ID's. Go to OsaSync - Options - Advanced Options, click Remove ID's
  • Uninstall OsaSync
  • Uninstall Outlook
  • Manually delete the following registry key: HKEY_CURRENT_USER\Software\Microsoft\Office\xx.0\Outlook
    (xx = 9 for Outlook 2000; 10 for Outlook XP; 11 for Outlook 2003; 12 for Outlook 2007)
  • Deleted all registry references to the .pst file (outlook.pst)
  • Reinstall Outlook
  • Reinstall OsaSync
  • Resync your folders

Errors during startup due to corruption in the pst file

While OsaSync was starting it encountered some errors. These errors are for 99% certainty caused by corruption in the .pst file. The pst file is the file in which outlook stores all data and is by default called Outlook.pst. These errors are severe and have to be solved in order to be able to work with OsaSync.

Repair your .pst file by following these steps:

- Empty your deleted items folder. Set outlook to empty the deleted items folder upon exiting (Tools - Options - Other - Empty the Deleted Items folder upon exiting).

- Run the Outlook Repair procedure

- Run the Inbox Repair Tool.

- Now start Outlook again and see if the error message is gone. If not you have to create a new PST file

- If this still doesn't solve the errors then create a new profile. Click here to see how to do this.

How to create a NEW pst file

(for Outlook 2000 directions click here)

  • Close Outlook.
  • Click Start, point to Settings, and then click Control Panel.
  • Double-click Mail and Fax. (If you do not have the fax service installed, double-click Mail.).
  • Click Data files.
  • Select the Personal Folders file and click Remove. If there are more pst files listed then remove them too.
  • Click Add, select Office outlook personal folders and click OK.
  • In File name box, type your first name. For example, if your name is Bob, type Bob, click Open, click OK twice, and then exit Control Panel.
  • Start Outlook and see if the OsaSync error messages are gone.

If this resolves the problem, you can import your information that is stored in your original Personal Folders (.pst) file.

Use the following steps to import your information:

  • On the File menu, click Import and Export
  • In the Choose an action to perform box, click Import from another program or file.
  • Click Next and select Personal Folder File (.pst), and then click Next.
  • In the File to import box, type the path of your Personal Folders (.pst) file, and then click Next.
  • Verify that Personal Folders is selected as the folder to import from and the folder to import into, and then click Finish

Error 48 (or error 429)  in proc: clsAImanager.Start. OsaSync menu stays greyed out.
or message: The OsaSync Outlook Add-in is unable to start the OsaSync.exe component

Outlook 2010  'click to run' version

If you run Outlook 2010 the problem can be linked to the fact that Office 2010 is sold and installed with the facility called “click to run” solution. That facility installs a new ‘virtual’ disk on your computer: Q.
You have to uninstall Windows 2010 ‘click to run’ version completely and reinstall another version that you can download on the Microsoft site. All is explained on the following link:

Outlook 2013/2016

  • Go to the folder in which OsaSync has been installed. Most likely C:\Program Files (x86)\OsaSync

  • right-click the file registerfiles_cs.bat and click Run as administrator

  • Several OsaSync files will be registered again in the Windows registry. You should receive a succes message afer each registration.

If re-registering the OsaSync files did not solve the problem, run the Outlook repair procedure

If that didn't help:

Most likely there is a problem with the OsaSync keys in your Windows registry. What usually helps in this case it to run a registry cleaner utility and remove ALL references to OsaSync.

- First uninstall OsaSync completely. Follow the procedure in so you don't have to reconfigure OsaSync later.
- From the Windows start menu, click run (in Win 10: click the search button next to the start menu button) and type 'regedit' to start regedit.
- Press Ctrl-f and search for OsaSync.exe (keep the checkboxes 'data', 'values', 'keys' checked). Here’s how the found result looks like:

-  Click on the key between {..} in the left window pane and press Delete.
-  Repeat this search with F3 until no more references are found. Delete all found references
-  In the left window pane, go to the top and click the Computer icon above the main registry keys
-  Repeat the search with Ctrl-f and search for OsaSync.clsInt. Delete all keys found
-  Install OsaSync again! Please be sure to install OsaSync as administrator

In 95% of all cased this solves the problem. If you happen to be part of the remaining 5% then more cleaning is required.
- Uninstall all outlook add-ins including OsaSync.
- See if there are other office related components installed on your computer like office viewers, web components, office BCM, etc, and uninstall them.
- See if you have any components of 2 different Outlook versions, e.g. outlook 2010 while there is still an Outlook 2007 program installed. If so choose one version and remove everything from the other version. If removing the previous office version fails here's help from Microsoft
- Reboot your pc and install OsaSync again.

Another approach is to bring your computer back to a restore point prior to the start of the problem. If that's possible carefully follow any new installations or updates to find out which program is interfering with osasync. Some applications that were reported to us as causing serious trouble to osasync are :
- update of AVG Addin for Outlook
- update of 2011 Windows Life Essential
- update of McAfee Addin

Error 429 or 196734 in procedure clsFolderMonitor.RDOSessionLogin: ActiveX component can't create object

When the OK button is clicked this message can be shown: An error occurred: COM object that has been separated from its underlying RCW cannot be used. This error can occur when OsaSync 2013 is started.

The osasync component vaMoreUtils.dll has not been registered correctly in Windows.

Solution (Windows 8):

  • Open the windows command prompt as an administrator (right click start button - choose 'command prompt as admin'
  • Type: cd "\program files (x86)\OsaSync2013"
  • Type: regsvr32 vamoreutils.dll This should register the file vaMoreUtils.dll in Windows and you should get a success message.

Error 91 in: clsInterface.AcceptOCXparams and NO OsaSync menu

Chances are you have not yet ran the connection wizard TO the computer that gives this error.

To make sure this is the case open the computername_vosaddin.log file and look for a line like this:
'clsComputers.EnumComputers: Wizard hasn't run FROM \\LAPTOP TO this computer, folder does not exist: C:\folder\OsaSync_Data\LAPTOP'. (C:\folder is the folder in which the OsaSync connection wizard has created the OsaSync_Data folder)
Run the connection wizard from the other computers(s) TO this computer.

Error 265 Error in IMAPIProp.SaveChanges: MAPI_E_OBJECT_CHANGED

This error indicates that most likely some other process has already modified the contact or appointment but not yet saved it. Is so, Outlook prevents another attempt to save the item, in this case when OsaSync tries to save a change made.
Best is to carefully inspect your other add-ins or anti-virus software to find out if one of these apps is interfering with OsaSync. You can do so by following this steps lined out here

Win95/Win98/Win2000: unable to register the DLL/OCX: DllRegServer failed for cProgBar.ocx

Download and install a version of MSVBVM50.dll version Now setup will continue.

You can download this version by clicking here. The file is MSVBVM50.ZIP. Unzip the file, put it in the Windows\System32 folder (Win95 the Windows\System folder) and register this file in Windows by typing from the commandline:
regsvr32.exe c:\windows\system\msvbvm50.dll.

Error 2 in procedure: clsComputer.ReadFromRegistry

This error indicates that the registry key HKEY_CURRENT_USER\software\osasync\computername\login has not been created (computername is the name of one of your computers). This is done by the OsaSync connection wizard so its best to rerun the connection wizard TO this computer from computer computername.

Error 11 in procedure: clsComputers.ConnectToFTPsrv. Division by zero

When Outlook and OsaSync start then OsaSync tries to connect to the FTP server for 10 seconds. If a connection within 10 seconds could not be established then start-up continues. In some cases however this error 11 can occur when connecting was impossible. If this happens then the time-out period of 10 seconds is to short in your network environment and should be increased. You can increase the ftp timeout value (start with 20 seconds) on the OsaSync ftp options window, accessible from the OsaSync advanced options page.

Error in registry for extension "Exchange Extensions"

After installing a new version (and sometimes even without that) you can get the error: Error in registry for extension "Exchange Extensions".
The solution to this to simply reset the key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\Client\Extensions\Exchange Extensions
back to its old value "4.0;emsuix32.dll;7;011111111111110;1111011100".

Error 52; Bad file name or number

OsaSync could not create a (temporary) file or could not read a file. If this error occurs while running the connection wizard and you have specified a (local) folder name make sure this name is valid.

Also see Error 75 or #76; Path/File Access Error or Path not found

Error 70; 75 or 76: Permission Denied;  Path/File Access Error or Path not found

OsaSync could not read a file from the shared folder on the other computer in which OsaSync has been installed.
Make sure this folder has read/write/delete access rights for the users from the other computers.

Try to manually create/delete a file in the \OsaSync_Data (or OsaServer)\ComputerName folder from another computer using My Network Places (or Network Neighborhood). Select the computer in the list of networked computers; browse to the \OsaSync_Data\ComputerName folder; right-click the folder and click on the Explorer menu bar File - new - text document (or text file). Give this file a name; open the file (double click it) and add some text. Then close the file and delete it. These operations should all be possible in order for OsaSync to be able to use this folder. If you can't do this and get a Windows messages telling you that you don't have the appropriate authorization then check out the Share permissions and the NTFS permissions. Both permission types have to allow all operations (In Windows XP you can only check NTFS permissions easily if simple file sharing is disabled). Consult your windows documentation or a Windows consultant if you have difficulties setting the appropriate permissions.

After the access permissions have been set rerun the OsaSync connection wizard to make sure the folders used by OsaSync are valid.

If access permissions are Ok but the errors persist then check your firewall and anti-virus software. Make sure your local network is added to the trusted zone in your firewall. Issues have been reported with Norton firewall and with ZoneAlarm Antivirus. Completely disable your firewall and anti-virus program to find out if it's causing the problem.

Outlook message: 'The note will close and your changes will not be saved'

When saving a note Outlook can show this message 'The note will close and your changes will not be saved'.

This strange Outlook behavior  occurs when you close the note by clicking the X in the right corner of the note window but does NOT happen when closing the note using the close command from it's menu.

After uninstalling OsaSync Outlook shows a message it cannot find vaMoreUtils.dll

After you have uninstalled OsaSync using the 'uninstall  OsaSync' menu option it can happen that when Outlook starts it shows a message that it cannot find the file 'vaMoreUtils.dll'

To solve this close Outlook and delete the file extend.dat files in C:\Windows\Application Data\Microsoft\Outlook.
(or on WinNT/2000/XP: C:\Documents and Settings\<user>\Local Settings\Application Data\Microsoft\Outlook).  If you cannot find the file you can use the windows search 'for files or folders' function. In XP: make sure to INCLUDE HIDDEN FILES in your search!

If this doesn't solve it then in the Outlook menu choose Tools - Options - Other - Advanced Options - Add-In Manager.  If there is an Add-in listed with the name 'Redemption helper extension' or 'Redemption helper Outlook extension' then deselect this Add-in and click OK to close this window.


An error occurred while trying to replace the existing file: DeleteFile Failed: Code 5 Access is denied

When upgrading you have to close Outlook.
But even when Outlook is closed, sometimes Outlook still locks the OsaSync.dll file. Restart your computer will always solve this.

Note: make sure Outlook is not in your start-up folder because otherwise Outlook is started again.


Error # 339 Procedure clsManager.Start: Component cProgBar.ocx or one of its dependencies is not correctly registered.

The file cProgBar.ocx is a file used by OsaSync. If this error occurs then the OsaSync installation process could not correctly install and register the cProgBar.ocx file. To fix this rerun the installation process: Make sure Outlook is closed and double click the file OsaSyncPROSetup.exe. If the installation process cannot install a file then cancel the installation process; restart your computer and repeat the installation.


Peer-to-Peer mode: I ran the connection wizard on both computers but no computers show on the OsaSync options window

You have installed OsaSync and you ran the OsaSync connection wizard on both computers and configured OsaSync in peer-to-peer mode but when you restart OsaSync a message is shown that no computers are configured. Also, the OsaSync options window doesn't list the computer that I have just configured.

What has happened:
It is most likely that the OsaSync_Data folder in which OsaSync in peer-to-peer mode saves it's temporary data is not the same folder on both computers. We can find this out by examining the vosaddin.log files and osasync.log files of both computers:

  1. Make sure OsaSync has been restarted at least once after you ran the connection wizard
  2. On each computer open the osasync.log file (vosaddin.log file prior to OsaSync 6.0). Click here for the location of the log files.
  3. Look for lines like the following in the beginning of the logfile (on computer VAITA-VAIO):
    clsComputers.GetP2PComputers: Wizard hasn't run FROM \\VAITA-XP TO this computer, folder does not exist: C:\OsaSync_Data\VAITA-XP
    clsManager.Start: #computers configured: 0

    The folder C:\OsaSync_Data\VAITA-XP does not exist so what happened when we ran the wizard on computer VAITA-XP? In the logfile from VAITA-XP we see:
    clsComputers.GetP2PComputers: SavePath = C:\data\Shared\OsaSync_Data\VAITA-VAIO
    clsComputers.GetP2PComputers: RemotePath = \\VAITA-VAIO\D_share\Data\OsaSync_Data\VAITA-XP
    clsManager.Start: #computers configured: 1
    clsManager.FillComputerArray: computer set to sync/share with: \\VAITA-VAIO ID: P002 connectmode = P2P

    Look at the path displayed as the RemotePath. This is the folder path on computer VAITA-VAIO where OsaSync on VAITA-XP looks for changes made by computer VAITA-VAIO. This folder has to be the same folder as the folder OsaSync on VAITA-VAIO expects to see. The folder C:\OsaSync_Data\VAITA-XP on VAIO is NOT the same folder as \\VAITA-VAIO\D_share\Data\OsaSync_Data\VAITA-XP : the folder is on D: instead of C: and in the subfolder \Data.

Run the OsaSync connection wizard again and make sure to select the same \OsaSync_Data folder on BOTH computers. So in this example we rerun the connection wizard on VAITA-VAIO and change the folder where OsaSync saves it's data on THIS computer from C:\OsaSync\Data to D:\Data\OsaSync_Data.

Have both computers use the same folder:
If you run the connection wizard on computer A and on computer B then the OsaSync_Data folder on A could be:
C:\Documents and Settings\All Users\Documents\OsaSync_Data
On computer B you have to select this same folder for computer A (step 8 in the connection wizard) but you don't see this same folder path but instead on computer B you see this OsaSync_Data folder on computer A in a SHARE like in \\Computer_A\shared files\OsaSync_Data.
If you are not sure if this is the same folder then use My Network Places on computer B to browse to the OsaSync_Data folder on computer A.


I installed OsaSync in peer-to-peer mode but I couldn’t get the sync to work.

First make sure configured OsaSync correctly in peer-to-peer mode. See our getting started page for a detailed step by step instruction on how to configure in peer-to-peer mode. What confuses some customers is how to set the OsaSync_Data folder. If two in peer-to-peer mode configured computers don't 'look' at the same OsaSync_Data folder then synchronization won't work. For more help on setting the OsaSync_Data folder click here.

When OsaSync has been configured correctly make sure you ran the prepare folders for synchronization wizard on one computer only. If not then:

  • First explicitly stop the folder syncing on both computers
  • Clean up all possible remaining OsaSync files from a previous synchronization attempt. Manually delete all files in the computername subfolder(s) of the OsaSync_Data folder. Do this on both computers.
  • Now rerun the prepare folders for synchronization wizard again on the computer that has the most items in the folder you are going to sync.

If after doing this the computers still don't sync then it's time to add a test item and to send us log files. Click here for details on how to do this.


I cannot sync, the “Prepare folders for synchronization…” button is gray

If the OsaSync menu item 'Prepare folders for synchronization..' is gray it is disabled.

The 'prepare for syncing' menu can be disabled temporarily:
When OsaSync is still busy with a long running process synchronization can't start. This happens when OsaSync is started; it takes some time for OsaSync to initialize, depending on the amount of folders in outlook. It also happens each hour when OsaSync goes through all folders to see if anything has changed. When these processes are ready the menu will be enabled again.

If the menu is never enabled:
In this case something is wrong. First restart Outlook to see if the problem remains. If so and you have just installed OsaSync then check if OsaSync 'sees' the other computers by reading this FAQ. If OsaSync isn't configured to see any other computer then running the 'prepare folders for syncing' wizard is not possible.

See also: Error 48 in proc: clsAImanager.Start. OsaSync menu stays greyed out.


Error nr: -2147467259: An unsent message cannot be flagged complete.

This error occurs when OsaSync import a message that is flagged complete and has been moved to another folder on the source computer.

OsaSync cannot handle messages that are flagged complete. A workaround is to move your messages to a synced folder before you set the follow up flag. Changes to this flag aren't synced and when you move the flagged message to another folder OsaSync will also move the same (non-flagged) message on the other computers.

After you have received this error message the imported e-mail is still in your Inbox folder. You can manually move the message to the destination folder.

Non-sequential OsaSync ID's

OsaSync displayed this message:
'WARNING: OsaSync sees that the OsaSync ID's are incorrect; assigned OsaSync ID's are not sequential!'.

This is what happened:
OsaSync created a new OsaSync ID for a new Outlook item and found that this new sequence number is not the highest number in the folder. This means that duplicate OsaSync ID's can exist in this folder or that they probably will be created in the future if you don't take action. When there are duplicate ID's then OsaSync can change the WRONG Outlook items!

How could this happen?
Normally all new ID's created by OsaSync have a higher sequence number than all existing ID's so this cannot happen if everything works well. This sequence number (the highest OsaSync ID) is stored in the default PST file.
(The highest OsaSync ID is set per computer, so not per folder.) The default pst file is the Standard delivery location.

If you changed the Standard delivery location to another PST file, OsaSync will use the sequence number from that PST file. Or the sequence number will start from 1 if it is a new PST file.
But there can be more ways that something went wrong.

How to solve this?
Delete all OsaSync ID's in the folder for which you get the warning. Do this by clicking the Remove OsaSync ID's button on the OsaSync advanced options window; tab Exception procedures. Then run the Prepare folders for synchronization procedure again on the computer on which  you removed the ID's. You do NOT have to remove the OsaSync ID's on the synced computer; OsaSync will assign new ID's automatically during the synchronization process on these computers.

Errors during downloading mail for my HOTMAIL account

HTML accounts like Hotmail are (currently) not supported in OsaSync. You can disable this top level folder in OsaSync by:
- Choose OsaSync - Options and click the button Advanced Options.
- Click the button Exclude folders... and select the name of the top level folder to exclude.

Cannot unset a Read-Only folder back to normal

Normally a Read-Only folder can be restored to a normal Read-Write folder by clicking the Undo Read-Only button on OsaSync's folder property window on a computer on which the folder is NOT Read-Only.

If for some reason this button is not visible it is possible to force OsaSync to show the button. The button will then also show on the computer on which the folder is Read-Only so it will then always be possible to reset the folder back to normal. To do this create the following entry in the Windows registry:

  • From the Windows start menu, click run and type regedit to start regedit.
  • Navigate to the key HKEY_CURRENT_USER\Software\OsaSync.
  • Click Edit - New - DWORD value in the regedit menu. Enter the name ForceROunsetBtn. In the right pane set the value to 1.

The Undo Read-Only button will now be visible when you go to the folder properties by choosing OsaSync - Synced folder - Properties...  

Script Error Object Required: 'page SBE', Line No:11

This is not an OsaSync error but an error produced by the Microsoft's SBCM addin (Small Business Edition Contact Manager). If this Outlook Synchronization manager is not used it is best to disable this addin via the tools - options - other - advanced options - comm addin dialog:

  • Uncheck the checkmark before 'Outlook Synchronization'. Do NOT remove it.
  • All contacts that have been created while the SBCM was running have been created from the contacts template 'IMP.Contact.SBE'. After disabling the SBCM add-in this template is not available anymore so the contact template of all existing contacts has to be restored to the default contacts template.
    OsaSync has a function for this:
  • From the OsaSync menu choose 'Options' - 'Advanced Options' and click the button 'Restore One-off items...'
  • Leave the text box empty and click 'Remove SBE reference'. OsaSync will now inspect every contact in every Contacts folder and restore the reference to the default contact template 'IMP.Contact'.

Duplicate tasks in the tasks folder and accepting assigned tasks is not possible

If you have synchronized the default tasks folder and you have assigned a task to someone it is possible that the task is duplicated in your tasks folder. Task delegation and synchronization of the tasks folder is not compatible. See the FAQ page for more info.

A folder appears to be out-of-sync, what to do?

If you have the impression that one or more of your folders are not in sync anymore with there corresponding folders on other computers then resynchronize the folder.

Outlook freezes after deleting an item or error 998 in proc: clsFldDelItmsWrap.ProcessItemDel

If I delete an item in Outlook (from any folder including the deleted items folder) then Outlook freezes (message at top blue bar says "not responding"). I have to force outlook to close. Or you get error messages when an item is deleted.

This happens because there are too much items in the deleted items folder. Please empty the deleted items folder and also instruct outlook to empty the deleted items folder upon exiting (Outlook menu: Tools - Options, tab Other).

If you don't want to delete the items that are now in the deleted items folder then consider creating other folders and move the items to those folders

OsaSync's menu items for synchronizing (check for changes, prepare for sync, etc.) are greyed out.

These options are greyed out if OsaSync is still busy with a long running process and not yet ready to start with syncing. This happens when OsaSync is started; it takes some time for OsaSync to initialize, depending on the amount of folders in outlook. It also happens each hour when OsaSync goes through all folders to see if anything has changed. When these processes are ready the menu will be enabled again. If that doesn’t happen then an error situation has occurred somehow. In this case restarting Outlook should enable the menu items again.

See also Error 48 in proc: clsAImanager.Start. OsaSync menu stays greyed out.

After upgrading OsaSync ActiveSync doesn't stay connected to my PocketPC

Upgrade to ActiveSync version 3.7 or higher.

OsaSync keeps displaying ' - initializing' and uses much CPU time

OsaSync never finishes initialization. The OsaSync menu keeps displaying ' - initializing' and OsaSync.exe keeps consuming a lot of CPU time. OsaSync is unusable and Outlook behaves sluggish.

Why does this happen:
Your Outlook profile has become corrupted.
Unfortunately the Outlook profile could become corrupted with OsaSync versions prior to 6.0.5 (especially with the 6.0.x versions in Outlook 2003). This could happen when a .pst or .ost file was added to the Outlook folder list by opening this file from the Outlook menu File - Open - Outlook data file.  If the profile has become corrupted and you try to close the pst file again by right-clicking the top level folder and selecting Close foldername then an Outlook error message is displayed and the file won't close. Now when Outlook and OsaSync is started with an invalid reference to a pst file then OsaSync keeps trying to read info from this file but cannot and enters a loop causing the high consumption of CPU time. This looping is endless so the initialization never finishes.

Install OsaSync version 6.0.5 or higher.
- Create a new Outlook profile

How to check a PST files for data corruption?

The .pst file(s) can be checked and repaired by running a Microsoft utility called the Inbox Repair Tool: scanpst.exe.

First close Outlook. Then locate the file on your computer by clicking Start - Search - For files and folders. Then type 'scanpst.exe'. The file will be found in a folder like
'C:\Program Files\Common Files\System\MSMAPI\1033' (Outlook versions prior to Outlook 2007)
'C:\Program Files\Microsoft Office\Office12'
  (Outlook 2007)
'C:\Program Files\Microsoft Office\Office14'  (Outlook 2010)
'C:\Program Files\Microsoft Office 15\root\office15  (Outlook 2013)
Run the program by double clicking it and choose Browse to select the .pst file to repair. If you get a message that the .pst file is still in use then close your virus scanner software (and other software that could be relevant). Repeat these steps if you have more .pst files.

If you are working with an Exchange Offline store (an .ost file) then use the repair tool scanost.exe. Here's how:

In order to check your Outlook installation files also run the Outlook repair procedure

If running the inbox repair tool did not solve the errors you should create a new pst file and copy the contents to this new file. Here's how

Duplicate items are created after syncing with my PDA

I synchronized with my Palm pilot (or another PDA) at the office, took my palm pilot home, synchronized with my home PC, returned to the office the next day, but when I synchronized, it created several duplicate contacts (not all) and double entries on the calendar. Is there a special way I should be handling this?

OsaSync assigns an OsaSync ID to each item in order to uniquely identify each Outlook item on multiple computers. The items on the home PC don’t have this OsaSync ID property because OsaSync isn’t used on that PC. When the Palm syncs with the home PC it receives copies of items from the home PC whenever the home PC was changed last. These copies don’t have an OsaSync ID so when the Palm syncs again with the OsaSynced PC, OsaSync regards the items without OsaSync ID as new items and creates new items.

The way to prevent this would be:
- Use your Palm syncing software to resync all folders from the OsaSynced PC with the Palm as an initial sync in order to copy all items from the PC to the Palm. These items will now all have an OsaSync ID.
- empty the folders on the home PC (make a backup copy of the .pst file first…)
- sync the Palm with the home PC. All items on the home PC now will have the OsaSync ID field.

When a new item is added on the home PC make sure it is changed on the OsaSynced PC (after is has been carried over by the Palm) BEFORE it is changed again on the home PC to prevent the same problem.

OsaSync PRO adds support for synchronization via an FTP server. This might be a better way to keep the work and home PC in sync.

OsaSync cannot process a .msg file

OsaSync shows the message: OsaSync cannot process the file filename. Manually open this file by double clicking it and add the contents to Outlook.

OsaSync processes changes from other computers by exchanging files. Some changes result in a .txt file and a corresponding .msg file. Example:  a change in an appointment notes field results in a file 000001.txt and 000001.msg. The .txt file tells OsaSync what the content is of the .msg file and in which folder it has to be imported. When OsaSync sees a .msg file but cannot find the corresponding .txt file it can't process the file anymore and the message is shown. You can import the msg file manually in Outlook. Use windows explorer to browse to the file and double click it. An appointment, task, contact or email item will open. Click File - Copy to folder to copy the item to it's appropriate folder. When the item is copied you can safely delete the .msg file.

In normal circumstances a txt file should never be missing. However this can happen sometimes when files are exchanged via an ftp server. If this happens more frequently then enable zipping and encryption on the OsaSync FTP options page. When ftp files are zipped this cannot happen.

Setting the follow-up flag results in the message The operation cannot be performed because the message has been changed

OsaSync makes a change to an email in the background whenever it has synced a change. If Outlook also changes the email and saves it, outlook can ´think´ that someone else has changed the email and shows the message. It happens only when an email is changed TWICE without saving after the first change. This can happen when:

  • The follow-up flag is clicked twice
  • Pictures are retrieved for the email because you clicked 'download pictures' and you move the email to another folder

To prevent this message save the email after the first change. You can simply force outlook to save a change to an email by clicking on another email in the folder list. So related to the follow-up flag:

  • Click the follow up flag
  • Click on the previous or next email in the folder list
  • Click the follow up flag again.

Save button is missing on Advanced Options Window

Saving options on the osasync advanced options window is not possible because the SAVE button is missing:


  • Right-click the file OsaSync.exe in C:\Program Files x86\OsaSync.
  • Click the setting Override DPI scaling behaviour:



Contact's phone number doesn't sync the '+' prefix

OsaSync simply syncs the content of the phone numbers field so it is Outlook that presents this field content on one computer with the '+' prefix and without it on the other. Outlook automatically masks all phone numbers according to your location settings.

Look at Control Panel > Phone and modem options...
Set your default dialing location the same on all synced computers.

Time difference of one hour between appointments on different computers

After syncing appointments there is a one hour time difference, so a meeting on one computer is starts at 9:00 and on the other computer this same meeting after syncing shows with a start time of 10:00.

Outlook uses daylight savings time on one computer while it doesn't on the other. Make this setting the same on both computers (Windows Control panel - Regional and language settings). Also check the time zone settings in Outlook: Tools - Options - Calendar options - Time zone..

Also see:

All day events are created as two days events on the other computer

This happens if your computers are in different time zones (or if 'Automatically adjust clock for daylight saving changes' is set on only one computer). An all day appointment is shown by outlook overlapping 2 days. This is Outlook behavior and it is not an OsaSync bug. Outlook saves all start- and end times internally in GMT time (Greenwich Mean Time). An all day event on February 4 is saved with start time 2/3/06 23:00 and end time 2/4/06 23:00 in a GMT+1 time zone. When this all day event is synced to a computer in time zone GMT+2 then the GMT times are still the same so it shows now in outlook as starting on 2/4/06 01:00 and ending on 2/5/06 01:00 and Outlook consequently shows the appointment overlapping 2 days.

Also see:

Appointment is not synced although everything seams to sync ok.

I have added an appointment but it doesn't show up on my other synced computer. There are no errors. When an appointment is added OsaSync creates a temporary file and when I click check for changes on my other computer this file disappears and OsaSync tells me that 1 file has been processed. Nevertheless I don't see the appointment in my calendar.

It is possible that the appointment is imported correctly on your synced computer but is now displayed on a different date (and that's the reason you don't see it). This happens when your computers use different windows date settings. If one computer uses the American date/time setting (MM/DD/YYYY) while the other computer uses the European setting (DD/MM/YYYY) then appointments will be imported on the wrong date. Example: an appointment on February 9 (2/9/2006) is imported on the computer with European settings on September 2.

Detect if this is the problem by looking at the reversed date (e.g. for 2/9 look at 9/2). You can also open the osasync.log file (vosaddin.log file prior to OsaSync 6.0) and look at the date/time at the beginning of each line. Compare this with the date/time in the osasync.log file of your other computer.

Correct this by setting the date format in control panel - regional and language settings to the same format on all computers.

If this doesn't solve it then follow the guidelines given here.

Also see:

Appointment on October 9th is synced as an appointment on September 10th

OsaSync syncs the start- and end dates of an appointment in the format ‘09/10/2005 9:00:00 PM’. It is Windows that interprets this date as October 9th if it uses European date/time regional settings or as September 10th if the computer has been set to American date/time settings.

So you will have to set the regional settings of all computers to accept the same date format (Windows Start menu, Settings, Control Panel, Regional and Language settings).

Also see:



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