Early Friday "there were nearly 113 incidents of people reporting issues with Microsoft 365 as of 1:05 a.m. ET," reports Reuters. But that's down "from over 15,890 reports at its peak a day earlier, according to Downdetector." Reuters points out the outage affected antivirus software Microsoft Defender and data governance software Microsoft Purview, while CRN notes it also impacted "a number of Microsoft 365 services" including Outlook and Exchange online:
During the outage, Outlook users received a "451 4.3.2 temporary server issue" error message when attempting to send or receive email. Users did not have the ability to send and receive email through Exchange Online, including notification emails from Microsoft Viva Engage, according to the vendor. Other issues that cropped up include an inability to send and receive subscription email through [analytics platform] Microsoft Fabric, collect message traces, search within SharePoint online and Microsoft OneDrive and create chats, meetings, teams, channels or add members in Microsoft Teams...
As with past cloud outages with other vendors, even after Microsoft fixed the issues, recovery efforts by its users to return to a normal state took additional time... Microsoft confirmed in a post on X [Thursday] at 4:14 p.m. ET that it "restored the affected infrastructure to a (healthy) state" but "further load balancing is required to mitigate impact...." The company reported "residual imbalances across the environment" at 7:02 p.m., "restored access to the affected services" and stable mail flow at 12:33 a.m. Jan. 23. At that time, Microsoft still saw a "small number of remaining affected services" without full service stability. The company declared impact from the event "resolved" at 1:29 p.m. Eastern. Microsoft sent out another X post at 8:20 a.m. asking users experiencing residual issues to try "clearing local DNS caches or temporarily lowering DNS TTL values may help ensure a quicker remediation...."
Microsoft said in an admin center update that [Thursday's] outage was "caused by elevated service load resulting from reduced capacity during maintenance for a subset of North America hosted infrastructure." Furthermore, Microsoft noted that during "ongoing efforts to rebalance traffic" it introduced a "targeted load balancing configuration change intended to expedite the recovery process, which incidentally introduced additional traffic imbalances associated with persistent impact for a portion of the affected infrastructure." US itek's David Stinner said it appears that Microsoft did not have enough capacity on its backup system while doing maintenance on its main system. "It looks like the backup system was overloaded, and it brought the system down while they were still doing maintenance on the main system," he said. "That is why it took so many hours to get back up and running. If your primary system is down for maintenance and your backup system fails due to capacity issues, then it is going to take a while to get your primary system back up and running."
"This was not Microsoft's first outage of 2026," the article notes, "with the vendor handling access issues with Teams, Outlook and other M365 services on Wednesday, a Copilot issue on Jan. 15 plus an Azure outage earlier in the month..."
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