Microsoft 365 outage enters second day as search issues persist

A widespread Microsoft 365 ↘ 0.24% disruption that began Monday morning has stretched into its second day, with the company reporting recovery of Exchange Online mail flow but continuing to work on restoring search functionality across multiple services.

The incident, tracked under identifiers EX1464935 and MO1465074, started around 11:55 a.m. UTC on August 31 when Microsoft began investigating an increase in user reports of Exchange Online problems. By early afternoon, the company traced the root cause to "an issue within a core authentication configuration used by multiple Microsoft 365 services".computerworld+2

The disruption rippled beyond email. Microsoft reported degraded or failed functions across Exchange Online, SharePoint Online, OneDrive for Business, Teams, Microsoft Purview, and Microsoft Defender XDR. Downdetector recorded thousands of user reports at the peak of the outage, with nearly 6,000 complaints logged for Outlook alone.mashable+3

Authentication Fix and Gradual Recovery

Microsoft spent several hours on Monday testing remediation strategies before beginning to reapply core authentication components across affected infrastructure starting at 6:40 p.m. UTC. The company progressively restarted targeted sections of infrastructure and expanded the mitigation incrementally.computerworld

By late Monday, Exchange Online mail connectivity had largely recovered, though Microsoft warned that some organizations could face delays as backlogged mail queues drained. OpenAI's ChatGPT Work service, which experienced a separate outage on the same day, was restored by approximately 4:05 p.m. ET Monday, according to CNBC.turkiyetoday+2

Search Remains the Sticking Point

As of early Tuesday, search functionality across Exchange Online, SharePoint, OneDrive, and Teams remained impaired. In its most recent update at 2:39 a.m. UTC on September 1, Microsoft said its remediation efforts had "yielded progress," with incremental improvement in service-health telemetry for search across a sample of the affected environment.computerworld

The company has not provided an estimated time for full resolution, saying only that it would share a recovery timeline "as soon as one becomes available". The prolonged disruption follows earlier Exchange Online incidents in 2026, including a mail-flow outage in June and mailbox access problems in April.sfcollege+2