Major outages and post-mortems
Microsoft 365 authentication outage starting August 31, 2026 disrupts email and Teams
Starting at 15:08 UTC (11:08 a.m. EDT) on August 31, 2026, Microsoft 365 users had trouble with Exchange Online email, Teams, OneDrive, SharePoint and other services, tracked as incident MO1465074. Microsoft linked it to an issue in a core authentication configuration shared across services, and recovery ran into the next day. Sign-in failures can look like a broken VPN or a home internet problem; check Microsoft’s status first. Published October 6, 2026.
- Event date
- Published here
- Updated
- Source
- Analytics Insight
What changed
On August 31, 2026, a Microsoft 365 outage began that disrupted email and collaboration tools for a large number of users. Analytics Insight reported that the affected services included:
- Exchange Online email (delays, failures, mailbox access and search problems);
- Microsoft Teams;
- OneDrive for Business and SharePoint Online;
- Microsoft 365 Copilot, Purview, Defender XDR and the Microsoft 365 admin center.
Microsoft tracked it as incident MO1465074. The statement quoted in the coverage says the disruption “stems from an issue in a core authentication configuration used across multiple Microsoft 365 services.” Microsoft worked on fixes by restarting infrastructure and applying targeted authentication fixes, and the outage was still going into a second day.
When
- Start: 15:08 UTC on August 31, 2026 (11:08 a.m. EDT). August 31 was a Monday.
- End: recovery ran into September 1; the coverage we read does not give a final end time.
Who is affected and what it means for you
Because the problem was in authentication, the step that checks who you are, it could show up in confusing ways: repeated sign-in prompts, apps that open but won’t load mail, or a company VPN or app that uses a Microsoft login refusing to connect.
Authentication failures are some of the easiest to blame on the connection. A sign-in that spins and times out feels like a network problem. On Starlink, people sometimes suspect CGNAT or IP geolocation when logins fail. Those can cause real problems. Our VPN guide covers CGNAT and VPNs, and Starlink’s support pages note that some services check IP location. But on August 31 the failure was Microsoft’s, and it hit users on every kind of connection.
A backup internet line wouldn’t have helped here.
What you can do now
- Check Microsoft 365 status, or ask IT, before changing VPN or router settings.
- Check your link in the Starlink app. If there are no outages and other sites load, the problem is upstream.
- Don’t reset passwords or MFA in a panic during a known sign-in outage; it can create a second problem once service returns.
- Keep a fallback channel for urgent work during long outages.
- Our video calls guide and troubleshooting page cover failures on your side.
What stays the same
- Starlink’s network and IP policy were not involved.
- Nothing changed in how Teams or Outlook use your connection.
What we don’t know yet
- The full timeline and a final root cause; we had not found a public post-incident report by October 6, 2026.
- How many users and regions were affected. The coverage describes a large number of users worldwide but gives no count.
- Our source is a news report quoting Microsoft’s status updates; Microsoft’s detailed incident notes are visible only to tenant admins.
Source
Microsoft Faces Mass Outage; Teams, Outlook, OneDrive, Copilot Down (Analytics Insight)
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