Microsoft 365 Outage Continues Into Second Day as Search Problems Linger

A widespread Microsoft 365 disruption that started Monday morning has moved into its second day. Microsoft has restored Exchange Online mail flow for most users but continues working to fix search across several services.

The company tracks the incident under identifiers EX1464935 and MO1465074. It began around 11:55 a.m. UTC on August 31 after Microsoft noticed a jump in user reports of Exchange Online problems. By early afternoon the team traced the root cause to an issue inside a core authentication configuration that multiple Microsoft 365 services share.

The problem spread beyond email. Users saw degraded or failed performance in Exchange Online, SharePoint Online, OneDrive for Business, Teams, Microsoft Purview, and Microsoft Defender XDR. At the peak, Downdetector logged thousands of complaints, including nearly 6,000 for Outlook alone.

Authentication Fix and Gradual Recovery

Microsoft spent several hours Monday testing possible fixes. At 6:40 p.m. UTC the company started reapplying core authentication components across the affected infrastructure. Engineers then restarted targeted sections and widened the mitigation step by step.

By late Monday, Exchange Online mail connectivity had largely returned. Microsoft noted that some organizations might still see delays while backlogged mail queues clear. OpenAI’s ChatGPT Work service, which faced a separate outage the same day, came back online around 4:05 p.m. ET Monday.

Search Remains Impaired

Early Tuesday, search still did not work properly across Exchange Online, SharePoint, OneDrive, and Teams. In its update at 2:39 a.m. UTC on September 1, Microsoft reported that remediation efforts had produced progress. Service-health telemetry for search showed incremental improvement in a sample of the affected environment.

Microsoft has not given an estimated time for full recovery. The company said it will share a timeline as soon as one becomes available. The incident follows earlier Exchange Online problems in 2026, including a mail-flow outage in June and mailbox-access issues in April.