Office 365 - MAPIInitialize fails - April 2020

Update (4/30/20):

Microsoft has reportedly fixed the issue in an update to Outlook. To check for the update:

1. Open Outlook, click File in the top left and then select Office Account.
2. Click the button beside Office Updates.
3. Choose Update Now

Let the update run, then reboot your PC. This will fix the issue with MAPI Initialize.

The fixed version is Version 2004 (Built 12730.20236 Click-to-Run) and 2006 (Build 12829.20000) for the Office Insiders. If you are still having issues you can try our Fix Tool below.

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For some people after the April 22nd Office 365 update, Sync fails with CompanionLink, and other products that use Windows Messaging API (MAPI). Here is the fix:

1. Download Fix 365 MAPI on your PC.
2. Run it - it will show a small dialog
3. Reboot your PC.

This program sets the registry to add two path values. These values fix a missing dependency in the April 2020 Office 365 Update.

More Information

Starting on April 22, 2020 this code snippet started failing:

 HRESULT hRes;
 MAPIINIT_0 MAPIINIT= { 0, MAPI_MULTITHREAD_NOTIFICATIONS};
 hRes = MAPIInitialize(&MAPIINIT);

This code has been running without a problem since at least the year 2000 (20 years).

This failed on at least one computer after an Office 365 Update. However, this problem is associated with several different Outlook versions:

Office 365 Version 2005 - 16.0.12823.20000 64bit - Windows Insider.
Office 365 Version 2003 - 12624.20520 (Click to Run) - Current Release.

So far - only on Windows 10.

We have also heard that All Add-Ons that rely on MAPI are failing. A customer has reported success when they rolled their Outlook Update back one version. We are going to post steps here shortly.

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For CompanionLink - One workaround is to turn off MAPI. To do this:

1. Exit CompanionLink (use Task Manager and End Task if CompanionLink is locked up.)
2. Run CompanionLink
3. Press Ctrl-Shift-U for the Settings Popup
4. Check the box to "Disable MAPI"
5. Hit Ok.

At this point CompanionLink will run normally.

Manually Disable the MAPI 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".
3. Now in the folder below, find "ClxMapi64.exe" and "ClxMapi.dll". Rename these files "ClxMapi.dll.old" and "ClxMapi64.exe.old".
4. 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.