Some users may have been unable to access Office.com or the Microsoft 365 Copilot web sign‑in page

Title: Some users may have been unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may have been unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: Users could've accessed Microsoft Copilot through application-based Microsoft Copilot services. This included, but wasn't limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps As a workaround, users may have been able to leverage https://m365.cloud.microsoft/search to sign in using this page. Once signed in, users could've accessed Office.com. Final status: We've concluded our extended period of monitoring and confirmed impact has not reoccurred. Scope of impact: Impact was specific to some users who were served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC End time: Tuesday, March 17, 2026, at 4:05 PM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page was receiving a high volume of traffic that inhibited the rate at which some users' requests were being processed, preventing some users from accessing the service pages. Next steps: - We're reviewing performance data and trends on the affected infrastructure to help prevent similar impact from happening again. - We're monitoring service telemetry to ensure impact does not reoccur. This is the final update for the event.

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impact to Office.com is still occurring, but the impact to Microsoft 365 Copilot web clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of March 17, 2026, at 4:05 PM UTC. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access Office.com. Current status: While our telemetry indicates that the impact is largely remediated, we’re continuing to monitor the environment as our traffic optimizations are nearing completion. We're proceeding with the monitoring process to ensure the service is stable and to determine whether any additional mitigative steps may be necessary to fully resolve this issue. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Wednesday, March 18, 2026, at 3:00 PM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impact to Office.com is still occurring, but the impact to Microsoft 365 Copilot web clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of March 17, 2026, at 4:05 PM UTC. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access Office.com. Current status: We're continuing to monitor our service health telemetry to ensure that all users regain access to Office.com as our configuration changes are applied to the remaining affected environment. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Wednesday, March 18, 2026, at 12:30 AM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impact to Office.com is still occurring, but the impact to Microsoft 365 Copilot web clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of March 17, 2026, at 4:05 PM UTC. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access office.com. Current status: Our service health telemetry continues to suggest that our configuration changes are restoring access to Office.com. We're gradually applying our changes to further balance the request traffic and remediate the impact for all users. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Tuesday, March 17, 2026, at 10:30 PM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impact to office.com is still occurring, but the impact to Microsoft 365 Copilot web clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of March 17, 2026, at 4:05 PM UTC. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access office.com. Current status: Currently, the affected web client, office.com is still impacted. After applying configuration changes and rebalancing the request traffic, the previously impacted Microsoft 365 Copilot web-clients, office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft, have recovered as of Tuesday, March 17, 2026, at 4:05 PM UTC. We've identified additional configuration changes and are proceeding to roll these out to the affected infrastructure. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Tuesday, March 17, 2026, at 8:30 PM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impacted web-client is office.com, and impacted Microsoft 365 Copilot web-clients are office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access the impacted web-based office.com and Copilot clients. Current status: We've applied our configuration changes and service health telemetry indicates some improvement; however, some users may still be unable to access Office.com. We're continuing to review the flow of request traffic to determine whether additional remediation actions are required. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Tuesday, March 17, 2026, at 8:00 PM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impacted web-client is office.com, and impacted Microsoft 365 Copilot web-clients are office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access the impacted web-based office.com and Copilot clients. Current status: We're continuing to apply configuration changes and rebalance the request traffic while monitoring service health telemetry to ensure the services recover. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Tuesday, March 17, 2026, at 11:42 AM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page is receiving a high volume of traffic that inhibits the rate at which some users' requests are being processed, preventing some users from accessing the service pages. Next update by: Tuesday, March 17, 2026, at 6:00 PM UTC

Title: Some users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page User impact: Users may be unable to access Office.com or the Microsoft 365 Copilot web sign‑in page. More info: The impacted web-client is office.com, and impacted Microsoft 365 Copilot web-clients are office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft. Users can access Microsoft Copilot through application-based Microsoft Copilot services. This includes, but is not limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage https://m365.cloud.microsoft/search, and should be able to sign in using this page. Once signed in, users can access the impacted web-based office.com and Copilot clients. Current status: We've identified that impact associated with MO1253428 has started to reoccur. We're reviewing traffic pattern telemetry and applying configuration changes to optimize connections and remediate impact. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Next update by: Tuesday, March 17, 2026, at 4:00 PM UTC