Microsoft said changes introduced to improve service availability were not producing the expected results, prompting engineers to explore alternative recovery measures.
The disruption affected Exchange Online and connected features across Outlook, Teams, Copilot and SharePoint, while some Teams functions continued operating.
The outage followed nearly 10 hours of disruption on Thursday, with Downdetector recording more than 130,000 reports of Outlook problems in the US at the peak.
Microsoft is exploring alternative measures to restore services affected by a widespread Microsoft 365 outage after changes introduced to improve service availability failed to deliver the expected results. In an update posted on Friday, November 13, the company's Microsoft 365 Status account said it had monitored the changes but found that they were “not taking as expected”. Microsoft said it was identifying alternative workstreams to increase capacity amid sustained traffic-management imbalances, indicating that the disruption could take longer to resolve.
The setback follows an outage that began on Thursday and disrupted Outlook, Exchange Online, Microsoft Teams, Copilot and other Microsoft 365 services. The company is tracking the incidents under reference numbers EX1550543 and MO1550821 in its Microsoft 365 admin centre. It directed administrators to these incident records for further information and provided an alternative status link for those unable to access the admin centre.
Microsoft Works On Alternative Measures After Recovery Efforts Stall
Microsoft's latest update came after earlier attempts to restore affected servers produced only limited recovery. The company had reported that some servers initially returned to service but became unresponsive again when they began receiving traffic. It was analysing diagnostic data with its networking and platform teams to identify what was triggering the failures.
The company had also introduced traffic-management measures, temporarily restricted certain types of requests reaching affected infrastructure in some locations and begun rebuilding a subset of servers using an earlier software configuration. These steps were intended to establish whether the previous configuration could prevent servers from becoming unresponsive. Microsoft said it would expand the approach if testing produced positive results.
The latest setback followed several hours of disruption on Thursday. Reuters reported that the outage lasted roughly 10 hours and affected businesses and government agencies across multiple countries. Downdetector recorded more than 130,000 reports of Outlook problems in the United States at the peak of the disruption.
Outlook, Teams And Copilot Among Services Affected
The disruption primarily affected Exchange Online, Microsoft's cloud-based email platform. Users reported difficulties accessing mailboxes through Outlook on the web and desktop applications, while email delivery and other Exchange-dependent functions were also disrupted. Microsoft said the impact extended to features of Teams, Copilot, SharePoint Online and other services that rely on Exchange Online data.
However, not every feature across these platforms was necessarily unavailable. Microsoft indicated that some Teams functions, including core calls and meetings, continued to work, while features dependent on Exchange Online were affected. OpenAI and Anthropic also reported problems with their Microsoft 365 connectors during the disruption.
Microsoft has not announced a definitive timeline for full restoration. Its latest update suggests that engineers are still working to stabilise affected infrastructure and restore capacity without triggering further server failures.
