🔍 Read the full analysis: Are You Affected By The Microsoft 365 Outage? What To Do Next on ThorstenMeyerAI.com
Get business pricing on monitors, keyboards and dev gear
- Business-only prices and quantity discounts
- Tax-exempt purchasing
- Multiple users, one account, clear invoices
TL;DR
Microsoft 365 was still experiencing a service degradation at 08:35 UTC on Nov. 13, after an outage affecting Exchange Online began the previous day. Microsoft reported improved server stability after a patch and was expanding it region by region; the root cause and full recovery timeline remain unknown.
Microsoft 365 remained in service degradation at 08:35 UTC Friday, Nov. 13, as Microsoft expanded a patch intended to stabilize infrastructure behind Exchange Online. The outage, which began Thursday, disrupted access to email and related services for users in multiple regions; Microsoft had not announced a full recovery or identified the root cause.
In an update at 08:06 UTC on incident EX1550543, Microsoft said servers were stable where it had applied a patch and that it was expanding the patch systematically, region by region. The company said it was beginning with regions at or approaching peak business hours. Its status page continued to list the incident as a service degradation 29 minutes later.
The primary reported issue is access to Exchange Online mailboxes through Outlook on the web, desktop and mobile apps, as well as REST connections. Microsoft’s incident notices said the disruption could affect service connectivity in any region. The supplied status information does not establish that every user or service in those regions was affected.
Because other products rely on Exchange Online, reported effects also include Teams calendars and meeting scheduling, parts of SharePoint Online, Microsoft 365 Copilot, the Microsoft Defender XDR portal, Purview and Planner. OpenAI and Anthropic separately reported errors with their Microsoft 365 connectors. Workhorse Group said it moved its third-quarter earnings call from Nov. 12 to Nov. 16 because of the outage.
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
Email Disruption Spreads Across Workflows
The incident matters beyond inbox access because Exchange Online supports connected work services. When mailboxes or related connections fail, users may also have trouble scheduling meetings, checking calendars or using tools that draw on Microsoft 365 data. The reported scope means businesses may face interruptions across several workflows even when a particular app appears available.
There are signs of business and third-party effects, but their scale is not fully established. Workhorse Group’s rescheduled earnings call is one specific example. OpenAI and Anthropic reported connector errors, but the available material does not quantify how many customers or tasks were affected. Reports on Downdetector indicate complaint volume, not a verified count of people unable to work.
For readers, the immediate distinction is between a patch showing progress and a confirmed restoration. Microsoft reported improved stability on patched infrastructure, but it was still extending the change and the status page had not marked the incident resolved. Users and organizations should treat service availability as potentially variable until Microsoft confirms recovery.
Popular right now
Hisense 75-Inch U7 Mini-LED ULED 4K UHD Smart Google TV (75U7SG)
Dyson Supersonic Travel Hair Dryer
Roborock RockNeo Q110H Wire-Free Robot Lawn Mower
As an affiliate, we earn on qualifying purchases.
How the Outage Developed
Microsoft’s first public notice came at 17:54 UTC Thursday, when its Microsoft 365 Status account said it was investigating reports of Exchange Online access problems in the Americas. A copy of the service-health notice on Cloud Admin Hub places the incident start at 16:17 UTC. At 18:07 UTC, Microsoft said the issue could affect connectivity in any region.
Microsoft’s updates described a sequence of troubleshooting steps. It initially cited elevated load across multiple regions, then said the load was not caused by increased traffic but by servers unexpectedly becoming unavailable. The company paused deployments, redistributed traffic and restarted servers. It later said returned servers could become unresponsive again when traffic resumed, and that a process responsible for establishing secure connections was becoming overwhelmed.
Microsoft then reported positive stability results after applying an upstream authentication and routing configuration component patch to part of its infrastructure. Downdetector reports cited by Reuters and Business Standard point to widespread complaints, but those services count user reports rather than confirmed affected people. A separate Teams incident, TM1550488, was marked resolved at 17:09 UTC Thursday; Microsoft has not said whether it was connected to EX1550543.
“Servers are stable where a patch was applied, and we are expanding the patch region by region.”
— Microsoft, in its 08:06 UTC service-health update for EX1550543
Recovery Scope and Cause Remain Unknown
Microsoft has not named a root cause, and the outage was still active on its status page at 08:35 UTC. Earlier updates mentioned failed automated health checks, an overwhelmed core process and a secure-connection process that stopped handling requests. Microsoft also said it had begun reverting a network configuration change that correlated with the start of the impact, but the available updates do not establish that this change caused the outage.
The company said it was not aware of malicious activity. That is Microsoft’s assessment, not a published incident investigation; the company said it would provide a Post-Incident Report after mitigation. It is also unclear how many users were affected, which regions or customers had recovered, and when the patch rollout would finish. User-report totals cited by news outlets should not be read as counts of confirmed outages.
Microsoft has not said whether the separately resolved Teams incident was related. Nor do the supplied updates give a confirmed restoration time for Exchange Online or its dependent services.
Watch for Patch Rollout and Resolution
Microsoft said it was expanding the patch systematically, starting with regions in or entering peak business hours. The next useful signal for users is a status-page update showing whether the rollout has reached more infrastructure and whether services remain stable as traffic returns. Until Microsoft marks the incident resolved, access may continue to vary.
Users who still cannot reach Microsoft 365 services can check Microsoft’s service-health information through their organization’s administrator and follow their workplace’s continuity procedures. Administrators should distinguish local connection issues from the broader incident and avoid treating a successful login or temporary recovery as proof that all dependent services are back.
Microsoft has promised a Post-Incident Report after mitigation. That report is expected to provide more information about the cause and response, but no publication time was given in the material available as of 08:35 UTC Friday.
Key Questions
Is the Microsoft 365 outage over?
No. Microsoft’s status page still listed service degradation at 08:35 UTC on Nov. 13. The company reported stable servers where it had applied a patch, but was still expanding the patch.
Which Microsoft 365 services are affected?
The main reported problem is access to Exchange Online mailboxes through Outlook and REST connections. Related effects have been reported for Teams calendars and meeting scheduling, parts of SharePoint Online, Copilot, Defender XDR, Purview and Planner. The precise impact can vary by user and region.
What should I do if Outlook is not working?
Check Microsoft’s service-health updates through your organization’s administrator and follow your workplace’s continuity procedures. Microsoft had not announced full recovery, so a temporary improvement may not mean all services are stable.
Has Microsoft explained what caused the outage?
Not yet. Microsoft described unavailable servers and an overwhelmed process affecting secure connections, and said it was reverting a network configuration change that correlated with the outage. It has not confirmed a root cause.
Was the outage caused by a cyberattack?
Microsoft said it was not aware of malicious activity. The company had not published its final investigation findings as of the latest status cited here.
Source: ThorstenMeyerAI.com
