Custom Agent Builder agent suddenly failing with "Oops, something happened" - no config changes

Hi, if nothing changed in the agent configuration, I would look at service health, grounding source access, and connector permissions first.

Quick checks:

1. Confirm Microsoft 365 Copilot service health.

2. Test whether the same user can open the grounding document directly.

3. Check whether the file moved, permissions changed, or sensitivity labels were applied.

4. Try a minimal test agent with one known-good document.

5. Capture the timestamp, user, and correlation ID if the error exposes one.

The "Oops" message is too generic by itself, so a minimal repro is your friend here. It helps separate agent config from backend/service behavior.