Microsoft 365 Alert – Service Degradation – Microsoft 365 Copilot Chat – Users are unable to submit a prompt in Microsoft 365 Copilot Chat and receive an error message – RESOLVED

16/06/2026 09:01:00 AM

NHSmail Reference: INC46851799

Microsoft Reference: CW1391746

Issue Status: RESOLVED

Issue Description: Users are unable to submit a prompt in Microsoft 365 Copilot Chat and receive an error message.

More info: Microsoft 365 Copilot Chat returned the following error message: “Something went wrong.” Some users were unable to submit a prompt in Microsoft 365 Copilot Chat and received an error message. Some users saw Copilot responses being provided successfully at first but then encountered an error message that overridden and removed the response after it had initially been generated successfully.

Final status: 16/06/2026 09:18:00 AM – Microsoft has confirmed with impacted users that the issue has been fully resolved. They appreciate your organization’s understanding and patience while they worked on addressing this incident.

Scope of impact: This issue affected some users when they tried to submit a prompt in Microsoft 365 Copilot Chat. This section was updated as our investigation continued.

Root cause: Microsoft has identified a code regression which was causing impact during prompt submission. They subsequently fixed the issue via a configuration update to disable the impacting portion of code.

Next steps: Microsoft is reviewing their change management practices to identify areas of improvement to prevent similar events from occurring in the future. They are analyzing their incident response readiness to find methods to reduce the time to mitigate and improve pre-incident detection signals.