Microsoft is investigating a widespread outage affecting multiple services across its Microsoft 365 ecosystem, including Outlook, Microsoft Teams and Copilot.

Users in numerous countries and regions have reported difficulties connecting to or accessing the platforms, disrupting email, collaboration and cloud-based services.

Multiple Microsoft services affected simultaneously

Technology news website BleepingComputer reported receiving numerous complaints from users experiencing problems with Microsoft services, particularly Outlook.

Many users said the email application was malfunctioning or unable to connect to its servers.

According to Downdetector, a platform that tracks service disruptions through user reports, complaints surged on Thursday afternoon, November 12.

Affected services included Outlook, Microsoft 365, Teams, Copilot, the Azure cloud computing platform, OneDrive cloud storage and Microsoft Store.

In an advisory published through the Microsoft 365 admin center under incident ID MO1550821, Microsoft confirmed that customers might be unable to connect to several critical services.

These included Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot and Microsoft Defender XDR.

The Microsoft 365 outage was recorded as beginning at 1:26 p.m. Eastern Time on Thursday, November 12, equivalent to approximately 1:26 a.m. on Friday, November 13, in Vietnam.

However, Microsoft said it had begun receiving and investigating reports of Exchange Online mailbox connectivity problems in the Americas earlier that day.

Unexpected server failures trigger widespread disruption

Microsoft initially suspected that the outage was caused by unusually high infrastructure loads across multiple regions.

Further investigation, however, revealed that the increased load was not the result of a sudden surge in user traffic.

Instead, several servers had unexpectedly become unavailable, forcing the remaining infrastructure to handle additional demand.

In an update posted on X, Microsoft explained that the elevated load was caused by unexpected server unavailability rather than increased traffic, and that engineers were working to safely restore the affected servers.

The unexpected failures shifted connection requests to operational systems, creating a cascading overload.

Because numerous Microsoft services rely on shared infrastructure, the disruption affected multiple platforms simultaneously.

To address the problem, Microsoft suspended all system deployments and began redistributing connection traffic across its global infrastructure.

The company also redirected additional traffic away from affected systems to reduce pressure on the remaining servers.

Engineers worked to restart failed servers, restore processing capacity and gradually return services to normal operation.

Although the initial Exchange Online disruption was primarily reported in the Americas, Microsoft subsequently confirmed that users in any region worldwide could be affected.

Early recovery signs emerge, but full restoration remains uncertain

In an update at 6:57 p.m. Eastern Time on November 12, equivalent to approximately 6:57 a.m. on November 13 in Vietnam, Microsoft reported initial signs of recovery after successfully restoring some affected servers.

Earlier, the company acknowledged that its mitigation measures had not produced the expected results.

Further investigation revealed that a core process running on the affected servers was overloaded, reducing their processing capacity.

Microsoft also began considering whether to reverse certain recently implemented configuration changes.

The company hoped that rolling back a limited number of configuration updates could accelerate recovery.

In its latest update on X, Microsoft said some affected servers had been brought back online and remained stable.

It added that engineers were redirecting traffic through alternative network routes wherever possible and had observed limited signs of improvement.

Microsoft said it had simplified the recovery process for the remaining affected servers.

However, users could still experience delays as applications reconnected to the restored infrastructure.

As a result, services were expected to recover gradually rather than simultaneously.

At the time of reporting, Microsoft had not provided a specific timeline for the full restoration of all affected services.

Hai Phong