Technology and Science01 September, 20262 min read
Microsoft Outlook And Exchange Online Outage Hits Microsoft 365 Services, Incident EX1464935
This article is an automated aggregation of coverage from news outlets. Our editorials offer in-depth analysis curated by the NewsCord team.
Exchange Online outages caused Outlook access, email delays, and authentication failures. Incident EX1464935 began Aug 31, 2026, with Microsoft investigating and working to restore.
9 outlets told this the same way.
Outage, auth misconfiguration
Microsoft Outlook and Exchange Online were hit by a widespread outage that began around 8 a.m. PT on Monday, with Downdetector showing a spike to more than 6,000 reports at 8:17 a.m. PT.
Microsoft said the root cause was “an issue with authentication configurations used by different Microsoft 365 services,” and its status page reported that “service telemetry continues to indicate recovery.”
By Tuesday morning, Downdetector showed fewer than 550 reports at 6 a.m. PT, though CNET reported that some users “may still experience hiccups” and that reported issues with Microsoft Outlook continued.
The Times of India described the disruption as entering its second day, leaving enterprise users unable to access platforms including Microsoft Teams, Microsoft 365 Copilot, OneDrive and Exchange Online.
In Microsoft’s own framing, the outage involved a core authentication configuration used by multiple Microsoft 365 services, and the company pointed administrators to incident EX1464935 in the admin center.
Search and Teams affected
As the outage persisted, Computerworld said search and other functions across Exchange Online, SharePoint, OneDrive, Teams and Microsoft 365 Copilot were still affected despite recovery of much of the Exchange Online mail flow. Computerworld reported that Microsoft identified “an issue within a core authentication configuration used by multiple Microsoft 365 services,” and that it spent hours testing how to restore affected authentication components and determine why they were not being deployed as expected. The Times of India quantified user impact via Downdetector, saying about 35% of users reported problems with the app, 35% clocked login issues and 18% were unable to access the website.
CNET reported that Downdetector tracked 37% of people reporting problems faced issues with receiving messages, 23% had trouble using the app and 20% reported issues with the website. In Microsoft’s status updates, the company said it was applying a targeted authentication component fix across remaining affected infrastructure and maintaining extended monitoring across affected service workflows.
Mitigation, monitoring, timeline
Microsoft told CNET it was “reexamining recent changes made to the service to determine why the authentication components aren’t being deployed as expected,” and it said it was exploring ways to safely restore the components, including reverting an update. CNET also reported that at 3:50 p.m. the status page offered information but “no estimated time for a complete fix,” while Microsoft continued extended monitoring across affected service workflows. TechCrunch said the outage was entering day two and that Outlook users should see “gradual recovery” to their mail flow, but it added that search functionality remained degraded as of Monday night.
Computerworld reported that Microsoft validated persistent recovery of mail flow and shifted its focus to restoring search functionality, while warning that some organizations could take longer to drain backlogged mail queues. Across the reporting, Microsoft’s incident tracking remained centered on EX1464935, with the company continuing remediation and testing while it worked toward full restoration.