Microsoft Service Advisory: Users may be unable to connect to, or experience degraded functionality with Exchange Online

Update timeline

1. investigating Aug 31, 2026, 04:28 PM UTC

   https://admin.cloud.microsoft/?#/servicehealth/:/alerts/EX1464935 Users may be unable to connect to, or experience degraded functionality with Exchange Online Issue ID: EX1464935 Affected services: Exchange Online Status: Investigating Issue type: Incident Start time: Aug 31, 2026, 11:53 AM EDT More info More info: Users may experience a variety of symptoms related to this event, including but not limited to: Delays or failures when sending or receiving email messages. Authentication-related errors when accessing Exchange Online services. Difficulties accessing or performing actions within Exchange administration experiences. Intermittent failures affecting mailbox operations and message delivery workflows. Scope of impact This issue may impact users attempting to send or receive email messages through Exchange Online. We're continuing our investigation to determine the full scope of affected scenarios and will provide additional information as it becomes available. Current status Aug 31, 2026, 12:16 PM EDT We're reviewing service telemetry and diagnostic data to isolate the source of the issue after receiving an increase in user-reported issues affecting Exchange Online. We'll keep refining the 'more info' section as additional impacts are identified. Next update by: Monday, August 31, 2026 at 1:30 PM EDT

2. investigating Aug 31, 2026, 10:04 PM UTC

   Microsoft has updated the incident as follows to expand to multiple services: Users may experience issues when utilizing multiple Microsoft 365 services Issue ID: MO1465074 Affected services: Microsoft 365 suite Status: Service degradation Issue type: Incident Start time: Aug 31, 2026, 11:08 AM EDT More info Impact includes, but may not be limited to, the below services and scenarios. We will update this list as our understanding of the issue progresses. OneDrive for Business and SharePoint Online: -Users may be unable to load or refresh portions of OneDrive and SharePoint, including account and storage information, search results, Favorites, Followed and Shared With Me content, recent files, lists, and news. Some users may also experience delayed or failed file opening, Office policy-label retrieval, OneDrive synchronization, mobile camera upload, and video playback. Users may see partial page failures, missing or stale content, repeated retries, and operation timeouts rather than a complete platform outage. Exchange Online -Users may be unable to connect to, or experience degraded functionality, with Exchange Online. All connection methods are affected. Microsoft Teams -Users may experience issues with calendar functionality and search. Users’ presence may be stale and not update automatically or through manual adjustment. User location adjustment may fail. Microsoft Purview -Users may face intermittent authorization failures across solutions in Purview. Purview admins can’t access the portal. Additionally, in Microsoft Purview Communication Compliance, users may see errors when loading Communication Compliance policies and Data Loss Prevention (DLP) policies. Communication Compliance policy creation and evaluation may be delayed. Microsoft Defender XDR -Users may experience intermittent authorization failures across solutions in Defender. Microsoft 365 Admin Center: -Admins may experience issues authenticating into the admin center. Universal Print -Users may be unable to create, upload, or retrieve print jobs. Scope of impact Users attempting to perform any of the outlined impact scenarios may be affected by this event. Preliminary root cause An issue within a core authentication configuration used by multiple Microsoft 365 services is resulting in impact. Current status Aug 31, 2026, 4:36 PM EDT We're reexamining recent changes made to the service to determine why the authentication components aren't being deployed as expected. Additionally, we are exploring every avenue to safely restore the components, including reverting an update the affected infrastructure recently received. We're performing additional tests to determine whether this will provide relief. Next update by: Monday, August 31, 2026 at 6:00 PM EDT

3. investigating Sep 01, 2026, 01:10 PM UTC

   Users may be unable to connect to, or experience degraded functionality with Exchange Online Issue ID: EX1464935 Affected services: Exchange Online Status: Service degradation Issue type: Incident Start time: Aug 31, 2026, 11:08 AM EDT More info We've confirmed that the authentication component issue impacts other services beyond Exchange Online. For more information regarding other impact scenarios, please see: MO1465074. We've opted to keep this post (EX1464935) open as Exchange Online remains the most predominantly impacted service. Users may experience a variety of symptoms related to this event, including but not limited to: - Delays, failures, or incomplete results when searching for content within Exchange Online mailboxes. - Delays or failures when sending or receiving email messages. - Authentication-related errors when accessing Exchange Online services. - Difficulties accessing or performing actions within Exchange administration experiences. - Intermittent failures affecting mailbox operations and message delivery work Scope of impact This issue may impact users attempting to send or receive email messages through Exchange Online. We're continuing our investigation to determine the full scope of affected scenarios and will provide additional information as it becomes available. Root cause An issue within a core authentication configuration used by multiple Microsoft 365 services is resulting in impact. Current status Sep 1, 2026, 6:58 AM EDT A substantial portion of the remediation deployment has been completed, and organizations whose environments remain affected are expected to recover as the deployment reaches the relevant infrastructure. As remediation progresses, we're focused on validating sustained recovery and monitoring for any remaining pockets of impact before determining whether any additional corrective actions are required. This quick update is designed to give the latest information on this issue. We recognise the impact this issue may be causing for your organization and want to assure you that resolving it remains our highest priority. We appreciate your patience and understanding as we continue working toward mitigation. Next update by: Tuesday, September 1, 2026, at 4:00 PM UTC

4. monitoring Sep 01, 2026, 01:11 PM UTC

   A fix has been implemented and we are monitoring the results.

5. resolved Sep 02, 2026, 01:26 PM UTC

   Sep 2, 2026, 2:44 AM EDT Our telemetry indicates service availability remains stable above 99 percent, and we expect the majority of users should no longer be seeing impact from this issue. Our continued focus is on balancing the implementation of our fixes across remaining portions of affected infrastructure to ensure persistent recovery, with added attention on ensuring withstanding recovery of scenarios dependent on REST and Graph API connection methods. This quick update is designed to give the latest information on this issue. Next update by: Wednesday, September 2, 2026, at 4:30 PM UTC