Microsoft 365 outage that left thousands unable to access email, Teams, other apps

Microsoft has identified the root cause of an outage that disrupted its Microsoft 365 services on Thursday morning, according to a company statement on social media.

By 9 a.m., over 23,000 users had reported issues with Microsoft 365 on Downdetector. The outage affected several key services, including Outlook, Teams, cloud services, Exchange Server, Skype for Business Server, and SharePoint, as per Downdetector data.

Around 75% of the reported problems were linked to Outlook.

“We’re currently investigating an issue where users may be unable to access multiple Microsoft 365 services. For more details and updates, refer to MO888473 in the admin center,” Microsoft 365 representatives shared in a post. “We are reviewing network telemetry and recent changes to our infrastructure. Additionally, we’re working with a third-party internet service provider (ISP) to identify the underlying issue.”

Later, Microsoft confirmed that a change implemented by AT&T was the cause of the outage.

“The ISP has since reversed the change, and we are now seeing signs of recovery,” Microsoft 365 representatives stated in a follow-up post.

This incident follows a similar disruption in July, when an update from CrowdStrike caused issues with Microsoft Windows operating systems, affecting major companies and airports