Today I received a call that Outlook 365 no longer starts. The “start window” appears briefly and disappears again after a few seconds. In the event log the following entry was created by the supposed crash:
Afterwards I tried to start Outlook in safe mode (Outlook.exe /Safe), which also worked. So first of all I tried to find out what the mso98win32client.dll is needed for. I didn’t find anything relevant here, but there have been problems with the DLL file in the past (with previous Outlook versions). That’s why I first tried the classic problem solutions:
- Repair Office (quick repair & online repair)
- Windows Updates installed
- Repair PST file (C:\Program Files (x86)\Microsoft Office\root\Office16\ScanPST.exe)
- New PST file created
Unfortunately, all without significant success. Finally I came across a forum entry that suggested rolling back the office update, which was the right solution for my problem. With the following error this “rollback” can be done:
“C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe” /update user updatetoversion=16.0.12827.20470