Failed fixes stretch the disruption past 12 hours as Microsoft rules out a cyberattack.
A Microsoft 365 outage knocked Outlook, Teams and other Office services offline worldwide from 12 November 2026. Microsoft says it has no sign of a cyberattack.
Microsoft 365 carries email, chat and documents for businesses, governments and schools, so a server fault spreads fast. TF tracks cloud failures and how organisations plan for them.
What’s Happening & Why It Matters
What Failed and When
Microsoft (@MSFT365Status) logged the first Exchange Online problems around 16:17 UTC on Thursday 12 November, per LazyAdmin. Downdetector showed almost 130,000 Outlook problem reports at the peak, per the Irish Times. The figures reflect user complaints, not a count of affected customers.
The Irish Times says the outage lasted more than nine hours. LazyAdmin counted about 12 hours 40 minutes by 04:57 UTC on Friday. A public mirror of Microsoft’s health feed still showed degradation at 10:04 UTC on Friday.
Exchange Online and Outlook suffered most. Teams calls and meetings fared better, but scheduling and invitations failed. Copilot, SharePoint, OneDrive, Defender, and Purview also had problems.
What Microsoft Says Caused It
Microsoft said a large number of servers went offline, shifting the load onto the rest. Servers failed automated health checks, and a secure-connection process was overwhelmed. Microsoft paused deployments on Thursday and reverted a recent network configuration change on Friday.
Microsoft’s explanation shifted. At 19:57 UTC on Thursday, it found no recent change matching the start. Hours later, it tied a network change to the start of the impact. Restarts worked at first, but restored servers failed again once traffic returned.
Microsoft says it has no sign of malicious activity. Australian Home Affairs Minister Tony Burke said Microsoft does not believe an attack is behind the fault. A post-incident report will give the root cause.
Who Felt It
Japan’s Government Solution Service was disrupted, and the Cabinet Office lost Outlook-based press distribution. Australian departments, federal police, courts and schools reported email problems. The US House of Representatives confirmed user effects, and Workhorse Group moved its results from 12 to 16 November.
Microsoft staff could not email, per the Irish Times. OpenAI and Anthropic both reported problems with their Microsoft 365 connectors. Mail is delayed and not lost, because senders retry.
What Admins Should Do
Track incident IDs EX1550543 and MO1550821 in the Microsoft 365 admin centre. Avoid local fixes such as profile resets or mail-routing changes. Use an approved backup channel for urgent messages.
LazyAdmin says Microsoft’s service level promises 99.9% uptime, and affected customers fall in the 50% credit tier. Credits are not automatic. Claims need incident IDs and impact times, with a 31 December 2026 deadline. Mark Gregory of RMIT says organisations should test updates before live rollout and keep a backup email.
My take: One configuration change took down email for governments and companies on three continents. Customers should treat Microsoft 365 as a single point of failure and plan a second channel.
TF Summary: What’s Next
Microsoft must confirm full recovery and publish the post-incident report. Customers will weigh service credits and backup plans. Regulators in Japan and Australia may ask Microsoft for a briefing.
MY FORECAST: Microsoft will publish a post-incident report naming a root cause before 30 November 2026. At least one national government will set backup email rules for agencies before 31 March 2027.
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