Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not have been retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and the date were not retrieved by Copilot Chat when prompted. While the affected email messages were being indexed to the semantic index model, users could've prompted Copilot Chat using exact wording to retrieve the email messages. Final status: We determined that the deployment fully saturated the environment and after a period of monitoring, we confirmed that the impact was remediated. Scope of impact: Some users who attempted to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and the present were impacted. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC End time: Monday, September 28, 2026, at 5:08 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, which resulted in the impact. Next steps: We're investigating why the misconfiguration wasn't identified during the testing and validation phases of the service change to help prevent similar issues in the future. This is the final update for the event.

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: The aforementioned deployment has saturated over 50% of the affected infrastructure and we've confirmed that some users are beginning to see remediation as the fix continues to propagate. Additionally, we expect that the remainder of the affected users will have received the fix deployment prior to our next scheduled update, at which point we'll monitor service health telemetry to ensure that impact is remediated and no additional mitigative actions will be required. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Tuesday, September 29, 2026, at 2:00 AM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: The initial 10% of the deployment has saturated throughout the affected infrastructure and has proven successful. We’re now in the process of deploying another 40% of the fix while we continue monitoring service health. Additionally, we expect that some users may be incrementally remediated as the deployment continues to saturate throughout the affected environment. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Sunday, September 20, 2026, at 3:00 AM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: We’re continuing to monitor the initial 10 percent deployment of our secondary fix, which is progressing as expected. We’ll continue monitoring service health and deployment progress before proceeding with the next phase and provide a timeline for full remediation once available. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Sunday, September 13, 2026, at 3:00 AM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: We've validated our secondary fix and begun the first 10 percent of deployment. We'll monitor this initial deployment process in order to determine the estimated timeline for full remediation and provide those details as soon as they become available. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Saturday, September 12, 2026, at 5:00 PM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: We're continuing to test the efficacy of our secondary fix to repair the affected email messages and will provide a timeline for the validation as one becomes available. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Saturday, September 12, 2026, at 3:30 AM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: We've confirmed that all new email messages are being indexed correctly as a result of our fix. We're testing our secondary fix with a subset of affected user mailboxes to repair the email messages that weren't indexed, so that we can validate its efficacy before we apply it to all affected users. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. This information may be updated as our investigation continues. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Friday, September 11, 2026, at 11:00 PM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: The fix to correct the code and ensure that future email messages will be indexed correctly is being deployed. In tandem we're repairing the affected email messages and indexing them to fully remediate the impact. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Friday, September 11, 2026, at 9:00 PM UTC

Title: Some users' Exchange Online email messages may not be retrieved when prompting Microsoft 365 Copilot Chat User impact: Users' Exchange Online email messages may not be retrieved when prompting Copilot Chat. More info: Some Exchange Online email messages between July 22, 2026, and today may not be retrieved by Copilot Chat when prompted. While we index the affected email messages to our semantic index model, users can prompt Copilot Chat using exact wording to retrieve the email messages. Current status: We've identified that a service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model. We're developing multiple fixes to ensure new email messages would be indexed and to index the email messages that were missed during the impact window. Scope of impact: Some users that are attempting to prompt Copilot Chat to retrieve details from Exchange Online email messages between July 22, 2026, and today may be impacted. Start time: Wednesday, July 22, 2026, at 10:07 PM UTC Root cause: A service change introduced a misconfiguration that prevented Exchange Online email messages between July 22, 2026, and today from being indexed by our semantic index model, causing impact. Next update by: Friday, September 11, 2026, at 7:30 PM UTC

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