"We determined the elevated load isn't driven by an increase in traffic, but by a number of servers being unexpectedly unavailable; straining the remaining infrastructure. We're working to safely return them to service," Microsoft said in an update on X.
Timeline of the disruptions
Microsoft logged the ongoing Microsoft 365 incident as beginning Thursday at 1:26 PM ET, according to a Microsoft 365 admin center advisory tracked as MO1550821. The company said it had earlier been investigating reports of Exchange Online mailbox connectivity problems in the Americas that same morning. Separately, Microsoft recorded an earlier Microsoft Teams incident tracked as TM1550488 that ran from 9:45 AM to 10:53 AM ET and has been fully resolved.
Scope: Which Microsoft services were affected
Users and monitoring services reported problems across a broad swath of Microsoft offerings. BleepingComputer received multiple user reports of trouble accessing Outlook and other Microsoft services. Downdetector showed a surge in user-submitted outage reports covering Outlook, Microsoft 365, Teams, Copilot, Azure, OneDrive, and the Microsoft Store. In its advisory, Microsoft confirmed customers may be unable to connect to Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot, and Microsoft Defender XDR.
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Get a security leadMicrosoft's technical diagnosis and mitigation steps
Microsoft initially attributed the disruption to elevated infrastructure load across multiple regions but revised that explanation after investigation. The company said the elevated load was not caused by increased traffic; instead, it concluded that "a number of servers [were] unexpectedly unavailable," which in turn strained the remaining infrastructure.
To reduce pressure on affected systems, Microsoft reported pausing all deployments, redistributing connection traffic across its worldwide infrastructure, and moving additional traffic away from impacted systems. The company also said it is restarting affected servers to restore capacity and return services to normal operation. Microsoft has not stated whether the earlier Teams incident (TM1550488) and the ongoing Microsoft 365 incident (MO1550821) are related.
User reports and monitoring signals
Outside of Microsoft's advisory, signals of disruption came from both crowd-sourced and direct user channels. Downdetector recorded a widespread spike in complaints Thursday afternoon for multiple Microsoft services. BleepingComputer received numerous reports from users experiencing access and connectivity problems, including complaints that Outlook was down. Microsoft acknowledged that while the company first reported Exchange Online connectivity problems in the Americas, it later confirmed users in any region could be affected by the ongoing incident.
What this means for IT teams, enterprises, and end users
- IT teams and administrators: Expect ongoing diagnostics and mitigation actions from Microsoft — the company has paused deployments and redistributed traffic while restarting impacted servers. Administrators monitoring Exchange Online and other tenant services should watch the Microsoft 365 admin center advisory MO1550821 for updates.
- Enterprises and procurement leaders: Services tied to Exchange Online, Teams, SharePoint Online, Microsoft 365 Copilot, and Microsoft Defender XDR were explicitly named in the advisory; organizations that depend on these services may need to continue contingency access plans until Microsoft restores full capacity.
- End users: Consumers and employees reporting errors in Outlook, Teams, or other Microsoft 365 apps should be aware Microsoft confirmed users in any region could be affected and that the company is actively working to return servers to service.
Microsoft confirmed the earlier Teams messaging incident (TM1550488) — which caused delays, failures when sending messages, errors creating or updating conversations, and problems retrieving chat messages — was fully resolved. The larger Microsoft 365 disruption tracked as MO1550821, however, remained unresolved as of the latest advisory. BleepingComputer said it contacted Microsoft with questions about the outage and will update its story if the company responds.
The immediate facts are straightforward: a global Microsoft 365 disruption accelerated when multiple servers became unexpectedly unavailable, Microsoft moved to throttle deployments and reroute traffic, and users worldwide reported degraded access to a range of services. Whether the earlier Teams incident and the later, broader outage are connected remains an open question that only Microsoft's ongoing diagnostics can answer.
