Microsoft 365 for Windows might crash while someone is just typing (you read that right). All the Office apps, Word, Excel, PowerPoint, Outlook or OneNote can be affected according to Microsoft, which knows about the problem and offers some workarounds.
The problem is caused by an out-of-date language pack which has all the spelling and other language info for Office. Outlook (classic) or other Office app crashes when it tries to spell check in a language with a mismatched language file. In some cases, the pack appears to be only slightly older but in others might be years old, depending on the setup.
The typing bug
In Microsoft 365 for Windows v2407 build 17830.20138 or later you can be typing away when suddenly the program just stops. Ouch. (As a guide, the current version is 2407 build 17830.20166 at 15 August 2024)
The only clue is in the Windows Event Viewer (click Start and search for ‘Event Viewer’) then search for Event 1000 or Event 1001 with one of these event logs or similar:
Faulting application name: OUTLOOK.EXE, version: 16.0.17830.20138, time stamp: 0x66aaad8c
Faulting module name: mscss7it.dll, version: 16.0.12527.20122, time stamp: 0x5e439ea1 Exception code: 0xc0000005
Fault offset: 0x000000000003e518
Faulting process id: 0x0x51B0
Faulting application start time: 0x0x1DAE97DD89190C3
Faulting application name: OUTLOOK.EXE, version: 16.0.17830.20166, time stamp: 0x66b7aa44
Faulting module name: mscss7ge.dll, version: 16.0.4288.1000, time stamp: 0x55f830b9
Exception code: 0xc0000005
Fault offset: 0x0000000000031991
Faulting process id: 0x0x506C
Faulting application start time: 0x0x1DAEE7B92076D82
We’ve put the faulting module name in bold. It will vary depending on the language dll causing the trouble, e.g. mscss7en.dll for English, or mscss7fr.dll, for French.
Microsoft says the problem is caused by a mismatched language file at C:\Program Files\Microsoft Office\root\Office16\ mscss7xx.dll which should be roughly the same version number as the main app. Look in the file properties to see the version/build details of any .dll file.
Workarounds
In the support forum, some users have temporarily fixed the problem by disabling automatic spell checking or “Check spelling as you type”.
Smart people in the forum identified the bug by disabling this option. The app worked OK until they did a manual spell check which triggered a crash.
Microsoft suggests a few workarounds:
- Do an online or full repair of Office. That should update all dll’s to the correct versions.
- If the dll files are quite old (Microsoft’s example is 16.0.4288.1000) that’s a stray MSI language pack. Perhaps left over from an installation years ago? Go to Setting | Apps | Installed Apps, look for any old Office language installation and uninstall it.
- Finally, uninstall all Language Packs and reinstall from Microsoft’s web site.
