Can’t open Office apps?

I'm somewhat surprised that we are still seeing a number of users affected by this bug as it was fixed several days ago. The issue? Some users are receiving an error message when they try to open any Office application:

"We're sorry, but Office App has run into an error that is preventing it from working correctly. Office App will need to be closed as a result. Would you like us to repair now?"

Repair is pointless and does not fix this problem. It’s a bug in current version, caused Microsoft Malware Protection Engine version 1.15700.*.

To fix, install definition updates for Windows Defender Antivirus and other Microsoft antimalware and restart the computer.

1. Type ‘Check for Updates’ on the start menu
2. Open ‘Check for Updates’ when it comes up.
3. Click Check for Updates and install any that are found.
4. Reboot the computer.

For more information see these articles:
Message when starting: PowerPoint has run into an error
Error when opening Microsoft Office apps