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SBaro94's avatar
SBaro94
Copper Contributor
Jul 02, 2026

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

 

Hi All,

We built a custom agent in Agent Builder (Microsoft 365 Copilot) that generates a Word risk assessment by grounding on a contract (either the document currently open via the Word Copilot add-in, or a file uploaded in the web browser chat), plus a fixed set of knowledge sources (guidance notes, playbooks). It worked reliably for about 5 days while I was testing it solo. We then rolled it out to appr. 20 users, and shortly after, it started failing consistently with a generic "Oops, something happened, try again" error, typically after a long delay, in both the Word add-in and the browser version.

 

I can't confirm causation, but the timing lines up closely with when we expanded from single-user testing to ~20 concurrent users. I don't know whether this points to a tenant-level capacity/concurrency limit being hit, or its something else, just stating it in case others have seen a similar threshold effect.

 

Is this a known concurrency/capacity limit for Agent Builder agents once usage scales up, or a separate backend regression affecting document grounding, and has anyone else seen this pattern after moving from single-user testing to broader rollout?

1 Reply

  • 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.