Microsoft 365 outage hits Outlook, Teams and Copilot worldwide

By Amara Osei

A Microsoft 365 incident that began at 1:26 p.m. ET Thursday disrupted Outlook, Microsoft Teams, Microsoft 365 Copilot and other hosted services worldwide, Microsoft said.

The company first reported Exchange Online mailbox connectivity problems in the Americas, but later confirmed that users in any region could be affected. The broader incident remained unresolved when BleepingComputer published its report, although recovery work was under way.

What did Microsoft confirm?

Microsoft's admin-center advisory MO1550821 said customers could not connect to Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR.

Downdetector, which tracks user-submitted outage reports, recorded a surge in complaints Thursday afternoon across Outlook, Microsoft 365, Teams, Copilot, Azure, OneDrive and the Microsoft Store. BleepingComputer also received numerous reports about connection problems, including complaints that Outlook was down.

Takeaway: The failure reached core collaboration, email, storage, security and cloud services rather than a single application.

What caused the disruption?

Microsoft initially attributed the disruption to elevated infrastructure load across multiple regions. It later determined that the load did not reflect an increase in traffic. A number of servers had instead become unexpectedly unavailable, placing strain on the remaining infrastructure.

In an update on X, Microsoft said: “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.”

Takeaway: More traffic did not cause the outage; missing server capacity did.

How is Microsoft restoring service?

Microsoft said it had paused all deployments. It redistributed connection traffic across its worldwide infrastructure and moved additional traffic away from affected systems to reduce the load.

The company also restarted affected servers to restore capacity and return services to normal operation. Those steps aimed to put unavailable systems back into service without placing further strain on the infrastructure.

Takeaway: Microsoft is buying capacity through restarts and traffic redistribution, but full restoration was not yet confirmed.

What happened in the earlier Teams incident?

The global disruption followed a separate Microsoft Teams incident earlier Thursday. That event, tracked as TM1550488, ran from 9:45 a.m. to 10:53 a.m. ET, a window of 68 minutes, and affected users in North and South America.

Users experienced delays or failures when sending messages, errors when creating or updating conversations, and problems retrieving chat messages. Microsoft attributed the incident to resource contention within its infrastructure.

That contention raised resource utilization and prevented Teams from processing messaging requests normally. Microsoft said the earlier Teams incident had been fully resolved.

Takeaway: The first outage ended before the wider Microsoft 365 incident began, and Microsoft has not established whether the two share a cause.

What remains unresolved?

Microsoft has not indicated whether the two incidents are related. It also had not resolved the ongoing Microsoft 365 outage at publication.

BleepingComputer said it had contacted Microsoft with questions about the outage and would update its report if the company responded.

Takeaway: The immediate operational response was active, but the cause of the server failures and the link to the earlier Teams disruption remained open questions.