Microsoft 365, Outlook, Teams and several other Microsoft applications remained disrupted for thousands of users for over seven hours on Friday, with the outage also affecting OpenAI and Anthropic's AI services through their Microsoft 365 connectors.
Reports of Outlook outages on Downdetector peaked at around 1.30 am on Friday, with 1,38,058 reports, before falling to approximately 34,490 by 4.30 am.
Microsoft, in a statement issued at 3.30 am on Friday, said it was working to restore the affected servers, with services recovering gradually as users reconnected.
Microsoft said its investigation had identified a process responsible for establishing secure connections on the affected servers as a key factor behind the disruption. The process was becoming overwhelmed, causing the servers to stop processing requests.
In its latest update, the company said it was preparing a configuration change to address the issue. The change was being tested on a subset of servers before being rolled out more widely, alongside restarts of the affected infrastructure.
Microsoft was also reversing a recent network configuration change that coincided with the start of the outage to determine whether it had contributed to the disruption.
The company said temporary traffic restrictions had been introduced in certain locations. It was monitoring the affected servers to check whether they remained stable while handling fewer connections, before gradually restoring additional traffic.
Earlier, the company had clarified that the problem was not caused by an overall increase in traffic, but by fewer servers being available to manage it.
"We are aware and investigating reports of users experiencing issues with Microsoft 365 services, primarily issues with Exchange Online," a Microsoft spokesperson said.
The outage affected several services that depend on Exchange Online and email infrastructure, although features that do not rely on these services continued to function.
WHAT MICROSOFT SERVICES WERE AFFECTED?
Exchange Online users faced difficulties accessing their mailboxes through Outlook on the web, desktop applications and mobile connections, while email delivery was also delayed.
The disruption extended to Microsoft 365 apps, where users were unable to access recently used files, and the Microsoft 365 admin centre, where some pages failed to load.
Microsoft Copilot was also affected, with users reporting difficulties loading Copilot Chat or receiving responses through web and desktop applications. Its ability to access work-related data, including emails, calendars and files, was also disrupted.
Microsoft Teams continued to support core messaging and online meetings largely normally.
However, features dependent on Exchange Online, including calendars, meeting scheduling and creating chats in organisations using Information Barriers, were affected.
Other impacted services included Microsoft Planner, Microsoft To Do, Microsoft Defender, Microsoft Purview, Microsoft Graph, Microsoft Fabric, Power BI, SharePoint Online, Universal Print and Windows 365.
The disruption also affected Microsoft 365 Education features, including Assignments, Reading Progress and Speaker Progress. Some Microsoft Intune services were also listed among the affected products.
Microsoft said features that did not depend on Exchange Online remained functional.
OPENAI, ANTHROPIC SERVICES ALSO HIT
The disruption extended beyond Microsoft's own applications to third-party services relying on its infrastructure.
OpenAI said it was investigating an issue with Microsoft connectors that could prevent new connections and cause tools to malfunction.
Anthropic said it had identified an issue with an upstream provider affecting its Microsoft 365 connector.
The outage also affected businesses. Electric truck maker Workhorse Group rescheduled its third-quarter results announcement from November 12 to November 16, citing business disruptions caused by the global Microsoft outage.
The incident comes weeks after Microsoft reported a disruption to its Azure cloud platform, which affected its productivity software suite and businesses across several industries worldwide.
Source: India Today