Microsoft blames a configuration change for Exchange Admin Center tumble

Microsoft took down the Exchange Admin Center (EAC) today after a code change left administrators facing an "Internal Server Error" when trying to access the service. Microsoft first admitted that something was amiss at 0937 UTC on October 12, noting, "When attempting to access the Exchange admin center, affected admins may encounter an 'Internal Server Error' message." Any administrator attempting to access the EAC could be affected. It was more than an hour before the company stated: "We've identified unexpected 302 redirect errors during affected Exchange admin center (EAC) access attempts and are analyzing diagnostic logs to isolate the source of the access failures. "While we continue our investigation, admins remain unable to access the EAC, with no workaround currently available." So, a fun morning for Microsoft's European users. According to Microsoft, the EAC is "a modern, web-based management console for managing Exchange Online." Want to manage mailboxes? EAC is where you go. Group management? Again, EAC. Microsoft explained: "The design of the EAC in Exchange Online aligns with the overall Microsoft 365 admin experience." Sadly, that alignment appears to extend to service wobbles caused by changes rolled out without due care and attention. Two hours after admitting things had gone awry, Microsoft said it was "continuing to test the rollback of the recent Exchange admin center (EAC) change while monitoring the results to determine if this resolves the impact." At this point, administrators were nodding sagely at an all-too familiar story. Of course rolling back the change did the trick. Microsoft stated as much in its final update: "A recent EAC configuration change resulted in unexpected HTTP responses within the affected request path, preventing admins from successfully accessing the EAC. "Reverting the identified change restored expected service functionality." Microsoft also assured customers it was reviewing the change to ensure it didn't make the same mistake again, as well as its monitoring and telemetry, to "improve detection and alerting for similar service behavior." The problem is that this is hardly a new phenomenon. In September, Microsoft made a configuration change that left some users unable to access SharePoint Online sites and pages. In April, another ill-thought-through change took down Outlook for iOS. And, in 2025, Microsoft 365 tumbled from the cloud because of yet another configuration change. It's almost as if testing changes consists of little more than asking Copilot, "does this look alright to you?" and then hitting the go button. The latest outage was resolved before the end of the working day, and a preliminary Post-Incident Report is due within two business days, with a final report due next week. Hopefully one or the other will contain words along the lines of "Hey, this keeps happening, maybe we should do some more testing before deploying to production?" (R)