Microsoft 365 Alert – Service Degradation – Microsoft Copilot (Microsoft 365) – Some users may be unable to open or use custom Copilot agents in Microsoft 365 Copilot and receive an error – RESOLVED

13/07/2026 08:12:00 AM

NHS.net Connect Reference: INC46877071

Microsoft Reference: CP1425545

Issue Status: RESOLVED

Issue Description: Users may be unable to open or use custom Copilot agents and receive an error.

More info: Impacted users report receiving an error stating “Something went wrong” or “Client error: Cannot read properties of undefined” and may encounter client crashes when attempting to open custom Copilot agents that were created through the Agent Builder in Microsoft 365 Copilot. User reports indicate that custom agents may still be accessible through Microsoft Teams.

Final Update: 15/07/2026 08:40:00 AM – Microsoft has successfully deployed the fix and confirmed with a sample of affected users that impact is resolved.

Scope of impact: Some users who are attempting to open or use custom Copilot agents that were created through the Agent Builder in Microsoft 365 Copilot may be impacted. This information may be updated as our investigation continues.

Root cause: A recent service change caused Microsoft Copilot (Microsoft 365) to receive incomplete data when loading the agent experience. As a result, the app couldn’t render the affected experience correctly for some users.

Next steps: Microsoft is reviewing their change procedures to help prevent the issue from reoccurring.