Outlook Invalid Class String
If you receive an Invalid Class String, try the following:
Quick Repair Outlook
Please use the following guide to run a quick repair of Outlook. Quick Repairing Outlook
If the error still occurs, we will need to disable two files in the CompanionLink folder.
You can achieve this automatically through CompanionLink settings:
- 1. Open CompanionLink
- 2. On your keyboard hit the key combination CTRL + SHIFT + U
- 3. In the window that opens, check the option "Disable MAPI", then click OK to save.
Or manually by renaming the two files:
- 1. Open the file explorer of Windows and navigate to C:\Program Files (x86)\CompanionLink.
- 2. Click the View in the top of the file explorer and on the right enable "File Name Extensions" if it is not already enabled.
- 3. Now in the folder below, find "ClxMapi64.exe" and "ClxMapi.dll". Rename these files "ClxMapi.dll.old" and "ClxMapi64.exe.old".
- 4. (Optional) Click the "File Name Extensions" options again to disable the extensions showing.
Once the MAPIs are disabled, restart the machine and try running the sync again.
If that does not work try doing a "Send/Receive All Folders" in Outlook, this can be done in the Send/Receive tab > click Send/Receive All Folders, after the Send/Receive is complete, restart the machine and try the sync again.