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

Title: Some users may be 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: The impacted web-client was office.com, and impacted Microsoft 365 Copilot web-clients were office.com/chat, m365.cloud.microsoft, m365.cloud.microsoft/chat and copilot.cloud.microsoft. Users could access 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 User may have been able to leverage office.com/search, which redirects to https://m365.cloud.microsoft/search, and should've been able to sign in using this page. Once signed in, users could access the impacted web-based office.com and Copilot clients. Final status: We've confirmed through our service-side telemetry that that the service health has fully recovered and impact has been successfully remediated. Scope of impact: Impact was specific to some users who were served through the affected infrastructure. Start time: Monday, March 16, 2026, at 1:05 PM UTC End time: Monday, March 16, 2026, at 9:55 PM UTC Root cause: The infrastructure that supports access to Office.com and the Microsoft 365 Copilot web sign-in page received a high volume of traffic that inhibited the rate in which some users' requests were being processed, preventing some users from accessing the service pages. Next steps: - We're continuing to monitor the affected infrastructure closely to ensure the service remains stable and to help inform any changes we can make to improve the service's resilience against similar issues in the future. 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 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 isn’t limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage office.com/search, which redirects to 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: Our service-side telemetry monitoring continues as we're seeing recovery from our latest configuration changes. We're monitoring further to understand if additional changes are needed. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Monday, March 16, 2026, at 1:05 PM UTC Next update by: Tuesday, March 17, 2026, at 2:30 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 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 isn’t limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage office.com/search, which redirects to 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 monitor our service-side telemetry to ensure our latest configuration changes are working as expected. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Start time: Monday, March 16, 2026, at 1:05 PM UTC Next update by: Tuesday, March 17, 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 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 isn’t limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage office.com/search, which redirects to 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: Our efforts to apply the aforementioned configuration changes are ongoing and we’re monitoring our service-side telemetry to ensure that the configuration changes are having the desired effect. In tandem, we’re determining the most efficient way to reproduce the event in our testing environment so that we can validate our progress. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Next update by: Monday, March 16, 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 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 isn’t limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage office.com/search, which redirects to 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: Through analysis of our service-side telemetry, we’ve made additional configuration changes to optimize traffic to the affected infrastructure. Our monitoring of service telemetry tracking successful and failed access attempts continues to ensure the effectiveness of these changes. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Next update by: Monday, March 16, 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 isn’t limited to: - Microsoft Copilot desktop app - Copilot in Microsoft Teams - Copilot in Office apps User may be able to leverage office.com/search, which redirects to 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: Our work to optimize the traffic to the affected section of service infrastructure continues. We've made additional configuration changes and are monitoring our service side telemetry to verify its effectiveness. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Next update by: Monday, March 16, 2026, at 6:30 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 Current status: We've identified that a section of service infrastructure is not processing traffic efficiently. We're making configuration changes to remediate impact. Scope of impact: Impact is specific to some users who are served through the affected infrastructure. Next update by: Monday, March 16, 2026, at 4:30 PM UTC