🔍 Read the full analysis: Is The Microsoft 365 Outage Still Affecting You? What To Know on ThorstenMeyerAI.com
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TL;DR
Microsoft’s Microsoft 365 status page still listed service degradation at 08:35 UTC on Nov. 13, after Exchange Online access problems began the previous day. Microsoft reported early stability gains where it applied a patch and said it was expanding deployment region by region; the cause remains unknown.
Microsoft’s Microsoft 365 outage was still ongoing at 08:35 UTC Friday, with the company’s status page listing service degradation after many users lost access to Exchange Online mailboxes and connected tools. In an update at 08:06 UTC on Nov. 13, Microsoft said servers were stable where a patch had been applied and that it was expanding the fix region by region; it has not identified the root cause.
The disruption began Thursday, Nov. 12. Microsoft’s first public notice, posted at 17:54 UTC, said it was investigating reports of problems accessing Exchange Online mailboxes through multiple connection methods in the Americas. Microsoft’s incident record, EX1550543, gives a start time of 16:17 UTC. Thirteen minutes after the first notice, the company said the issue could affect Microsoft 365 connectivity in any region.
Reported effects include difficulty reaching mail through Outlook on the web, desktop and mobile, as well as through REST connections. Services that depend on Exchange Online have also been affected, including Teams calendars and meeting scheduling, parts of SharePoint Online, Microsoft 365 Copilot, the Microsoft Defender XDR portal, Purview and Planner. The source report says OpenAI and Anthropic separately reported errors with their Microsoft 365 connectors.
Microsoft’s updates described a sequence of troubleshooting steps. The company first cited elevated load across regions, then said that load was not caused by increased traffic but by servers becoming unexpectedly unavailable. It paused deployments, redirected traffic, restarted affected servers and changed its server-health check approach. Microsoft later reported that some returned servers became unresponsive again under traffic, and said an overwhelmed process involved in establishing secure connections was stopping servers from processing requests.
Microsoft 365 outage · Nov 12–13, 2026 · times UTC
Down, rerouted, restarted, down again
How Microsoft described the outage, step by step, in its own status posts.
Server pool (schematic)
servingcarrying extra loadunavailablerestart
What Microsoft said
- 17:54Nov 12Mailbox access fails in the Americas
- 18:07“May affect” users “in any region”
- 18:35“Elevated load across multiple regions”
- 19:12All deployments paused, traffic moved, servers restarted
- 19:31Not more traffic: servers “unexpectedly unavailable”, the rest carry the load
- 21:00New health-check method: some servers back in service
- 23:59Returned servers “can become unresponsive again”
- 08:06Nov 13Patch stable where applied, now expanding region by region; still degraded
Hit
Exchange Online mail in Outlook, Teams calendars, SharePoint features, Microsoft 365 Copilot, Defender XDR portal, Purview and more
AI connectors
OpenAI and Anthropic reported errors in their Microsoft 365 connectors
Earnings call moved
Workhorse Group: from Nov 12 to Nov 16, citing the Microsoft outage
Sources: Microsoft 365 Status on X (Nov 12, 17:54–21:00 UTC); Microsoft service health EX1550543 (Nov 12, 23:59 UTC; Nov 13, 08:06 UTC) and status.cloud.microsoft MO1550821 (Nov 13, 07:29 UTC); Anthropic and OpenAI status pages; Workhorse Group press release, Nov 12, 2026. Server pool is a schematic, not real server counts.
Graphic: Powered by Thorsten Meyer AI
Outage Spreads Beyond Email
The incident matters because Exchange Online supports more than inbox access: connected Microsoft 365 services use it for functions such as calendars and meeting scheduling. When the underlying service is degraded, users may face problems across several work tools at once, even if those products are not themselves the origin of the fault.
The disruption has also affected organizations’ schedules and integrations. The source report says Workhorse Group moved its third-quarter earnings call from Nov. 12 to Nov. 16 because of the outage, while OpenAI and Anthropic reported errors with Microsoft 365 connectors. These examples show possible knock-on effects, but they do not establish how many businesses or users were affected overall.
Reports collected by Downdetector indicate a substantial volume of complaints, not a verified count of people without service. Reuters, as published by The Korea Times, reported more than 130,000 U.S. Outlook problem reports at a peak around 1 p.m. ET Thursday. Business Standard cited reports in 74 countries. Those figures should be read as user submissions on a reporting service, not as confirmed totals of affected customers.
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How Thursday’s Incident Developed
Microsoft’s public updates trace the incident from an initial report of mailbox access problems in the Americas to a warning that connectivity issues could affect users in any region. During Thursday evening and overnight, the company said it was trying to redistribute traffic and restore unavailable servers. It also said it had not identified a recent change that matched the start of the impact, while investigating failed automated health checks and a component responsible for processing server health.
By late Thursday, Microsoft said its earlier actions had not provided the expected relief and that a core process on affected servers was becoming overwhelmed. A Friday 01:06 UTC service-health update described a process responsible for secure connections becoming overwhelmed, and said Microsoft had begun reverting a recent network configuration change that correlated with the start of the incident. At 02:54 UTC, it said a change it had applied was not working as expected.
At 07:29 UTC Friday, Microsoft reported positive server-stability results after applying a patch to part of its infrastructure. At 08:06 UTC, it said the rollout was expanding systematically, starting with regions in or entering peak business hours. A separate Teams incident earlier Thursday, tracked as TM1550488, was declared resolved at 17:09 UTC; the available reporting says Microsoft has not clarified whether it was related to EX1550543.
“Servers are stable where the patch was applied, and we are expanding the patch region by region.”
— Microsoft, in its 08:06 UTC service-health update for EX1550543
Cause and Full Recovery Remain Unknown
Microsoft has not named a root cause, and the company has not said when the outage will be fully resolved. Its updates point to unavailable servers, failed health checks and an overwhelmed process involved in secure connections, while also describing a network configuration change that correlated with the impact. The relationship between these factors has not been fully explained.
It is also unclear how many customers remain affected, which regions have received the patch, and whether all connected Microsoft 365 services have recovered at the same pace. Downdetector submissions are not a verified measure of affected users. Microsoft said it was not aware of malicious activity, but that statement is not a final technical account of the incident.
Watch Microsoft’s Regional Rollout
Microsoft said it was expanding the patch region by region, prioritizing areas in or entering peak business hours. Users and administrators should check Microsoft’s service-health information for current availability rather than assume that stability in one region means the incident is resolved everywhere.
The next key update is whether Microsoft reports stable service across the affected infrastructure and changes the incident status from degradation to resolved. The company has promised a Post-Incident Report after mitigation. That report is expected to provide a fuller account of the cause and response, but no publication time was given in the source material.
Key Questions
Is the Microsoft 365 outage still affecting users?
Yes. Microsoft’s status page still listed service degradation at 08:35 UTC on Nov. 13. The company reported stable servers where a patch had been applied, but said it was still expanding the rollout.
Which services have been affected?
Reported problems include Exchange Online mailbox access through Outlook web, desktop and mobile, and REST connections. Related effects have included Teams calendars and scheduling, parts of SharePoint Online, Copilot, the Defender XDR portal, Purview and Planner.
What caused the outage?
Microsoft has not identified a root cause. Its updates describe unexpectedly unavailable servers and an overwhelmed process involved in secure connections, along with investigation of a network configuration change that correlated with the incident.
When will Microsoft 365 be fully restored?
Microsoft has not provided a full-restoration time. It said it was expanding the patch region by region; service status may vary while that work continues.
Was the outage caused by a cyberattack?
Microsoft said it had no indication of malicious activity as of its 04:10 UTC update. The company has not yet published its final incident report or named the root cause.
Source: ThorstenMeyerAI.com
