The Microsoft outage ended on Saturday, when the company said Outlook, Teams, Copilot and other applications had recovered fully after more than 24 hours.
Businesses and government organisations that run on Microsoft 365 had trouble reaching email, files and calendars during that time.
Microsoft restored all remaining customers and regions on Saturday
Microsoft said in a post on X:
“We have completed our efforts to address the underlying issue of the incident and restored service to the remaining impacted customers and regions.”
The outage began on Thursday.
Unavailable servers strained Microsoft’s infrastructure
Microsoft first blamed elevated load across its infrastructure in multiple regions. It later said traffic had not increased. Servers had become unavailable instead.
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.”
The company said it paused all deployments, redirected additional traffic away from the servers that failed and began restoring services.
Early fixes failed to hold
Microsoft first tested a configuration change for servers that were failing automated health checks. The change did not bring the expected relief.
The company found that a core process on the servers was becoming overwhelmed, which cut capacity. Some servers that returned to service became unresponsive again once traffic reached them.
Microsoft then redirected traffic through other routes, restricted certain types of traffic, adjusted network protocols and blocked traffic to stabilise servers. These steps produced partial recovery in some regions but no sustained restoration. Microsoft said it was exploring other approaches to traffic management imbalances.
Outlook, Copilot and file access failed while Teams messaging held
The outage hit services that depend on Exchange Online, Microsoft’s cloud based email and messaging platform. Outlook mailboxes failed to open on web, desktop and mobile applications. Email delivery slowed, and some users reported connectivity problems.
Users had trouble opening recently used files in Microsoft 365 applications. Some pages in the Microsoft 365 admin centre failed to load.
Copilot Chat failed to load or respond on web and desktop applications. Copilot could not retrieve emails, calendars and files.
Teams messaging and online meetings ran largely as normal. Calendars and meeting scheduling, which rely on Exchange Online, failed. Some users in organisations that use Information Barriers could not create chats.
The outage also reached Planner, To Do, Defender, Purview, Graph, Fabric, Power BI, SharePoint Online, Universal Print and Windows 365.
Microsoft outage reports passed 38,000 on Downdetector
Downdetector, a site that tracks user reports of outages, recorded more than 38,000 reports of Microsoft 365 problems on Thursday. It logged around 4,500 reports for Teams at about 2:07 PM ET.
OpenAI said it was investigating an issue with its Microsoft connectors that could stop new connections and cause some tools to malfunction. Anthropic reported an issue with an upstream provider affecting its Microsoft 365 connector.
The reports showed how an outage in cloud infrastructure spreads to services that rely on third party integrations.
Context: Azure outage in October 2026
Microsoft reported an outage on its Azure cloud platform in October 2026. It disrupted the productivity software suite and affected businesses across several industries. Read more business and technology coverage on Khusoko News.
