Some users may receive failures when prompting Microsoft 365 Copilot in Outlook on the web or the Outlook desktop client

Timeline (UK time)

1. 8 Oct 2026, 18:40 BST ✓ Operational

   Title: Some users may receive failures when prompting Microsoft 365 Copilot in Outlook on the web or the Outlook desktop client User impact: Users may have received failures when prompting Copilot in Outlook on the web or the Outlook desktop client. More info: Users may have received a "Something went wrong" error message when prompting Copilot in Outlook. Final status: We've rolled back the model migration that had resulted in degradation in Copilot prompt responses and validated after completing an internal monitoring period that impact is remediated. Scope of impact: This issue affected some users attempting to prompt Copilot in Outlook on the web or the Outlook desktop client, who may have received a "Something went wrong" error to their prompts. Start time: Thursday, October 8, 2026, at 1:20 PM UTC End time: Thursday, October 8, 2026, at 4:10 PM UTC Root cause: A recent model migration for Copilot in Outlook on the web and the Outlook desktop client resulted in an unexpected influx in user traffic and caused degradation in Copilot prompt responses. Next steps: - We're analyzing the problematic model migration to isolate why the potential for impact wasn't caught during our internal testing and validation phases. This further analysis will help us to prevent similar impact scenarios from occurring in the future. This is the final update for the event.

2. 8 Oct 2026, 17:33 BST ✓ Operational

   Title: Some users may receive failures when prompting Microsoft 365 Copilot in Outlook on the web or the Outlook desktop client User impact: Users may receive failures when prompting Copilot in Outlook on the web or the Outlook desktop client. More info: Users may receive a "Something went wrong" error message when prompting Copilot in Outlook. Current status: After analyzing available service telemetry, we've isolated that a recent model migration for Copilot in Outlook on the web or the Outlook desktop client is resulting in an unexpected influx in user traffic and causing degradation in Copilot prompt responses. We're rolling back the update and monitoring available telemetry for remediation. Scope of impact: This issue affects some users attempting to prompt Copilot in Outlook on the web or the Outlook desktop client, who may receive a "Something went wrong" error to their prompts. This section may be updated as the investigation progresses. Start time: Thursday, October 8, 2026, at 1:20 PM UTC Root cause: A recent model migration for Copilot in Outlook on the web or the Outlook desktop client is resulting in an unexpected influx in user traffic and causing degradation in Copilot prompt responses. Next update by: Thursday, October 8, 2026, at 6:30 PM UTC

3. 8 Oct 2026, 16:24 BST ✓ Operational

   Title: Some users may receive failures when prompting Microsoft 365 Copilot in Outlook on the web or the Outlook desktop client User impact: Users may receive failures when prompting Copilot in Outlook on the web or the Outlook desktop client. More info: Users may receive a "Something went wrong" error message when prompting Copilot in Outlook. Current status: Our service monitors have alerted us to a drop in availability for a subset of users attempting to prompt Copilot in Outlook on the web or the Outlook desktop client. We're reviewing available service telemetry to isolate potential sources of impact contributing to the drop in availability and to determine our next troubleshooting steps. Scope of impact: This issue affects some users attempting to prompt Copilot in Outlook on the web or the Outlook desktop client, who may be returned a "Something went wrong" error to their prompts. This section may be updated as the investigation progresses. Start time: Thursday, October 8, 2026, at 1:20 PM UTC Next update by: Thursday, October 8, 2026, at 4:30 PM UTC

4. 8 Oct 2026, 16:05 BST ✓ Operational

   Title: We're looking into a potential problem impacting Microsoft 365 Copilot User impact: We're checking for potential impact to your users. Current status: We're investigating a potential issue with Microsoft 365 Copilot and checking for impact to your organization. We'll provide an update within 30 minutes.