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

Hi,

Based on what you shared here it's difficult to conclude that concurrency is the root cause. The timing may just be coincidence. The error 'Oops something happened can also be related grounding issue, request timeout, or temporary backend changes. Since you are seeing the same result in both word app and browser it feels more like service side issue then something specific to client. if you haven't already, it might be worth trying with a smaller document, a simple prompt, or temporarily removing / different Knowledge source to see if the behavior changes. if it continues raising a Microsoft support ticket would probably be the best next step so they can investigate the issue from the service side. I just checked on my own tenant there was a service health issue (CP1410413) has been reported for similar kind of behavior.