Microsoft 365 users have found themselves unable to access the platform, or with spotty performance, following a massive global outage.

All elements of Microsoft 365 are affected in the incident, including Copilot, Outlook, Calendar, SharePoint, Planner, Admin Center and Apps Admin Center, Exchange Online, and some elements of Teams.

Windows 365 customers that have used Microsoft Purview to configure their tenant and Cloud PCs may also be unable to connect to those virtual PCs. Azure and Power Platform Admin Center aren’t affected, however.

While both consumer and professional versions of Microsoft 365 are affected, the impact on Business and Enterprise is far greater according to the Microsoft Health Status page.

Microsoft is updating customers on the situation both via the status page and social media platform X.

In addition to the impact on Microsoft 365, popular services from AI firms Anthropic and OpenAI were also impacted. OpenAI said that “new connections [to Microsoft 365 from ChatGPT] may be broken and tools are not working as expected”. A similar statement has been issued for Claude.

Microsoft 365 outage: Cyber attack ruled out, but fixes aren’t working

In an X update, the company said the issue was being driven by “a number of servers being unexpectedly unavailable; straining the remaining infrastructure”.

Microsoft's EVP of Copilot, agents, and platform said the incident wasn’t caused by a cyber attack, stating on X that “for now I can confirm that there is no indication this is the result of malicious or cyber activity”.

While the company said the increased load hasn’t been caused by excess traffic – which would have indicated a DDoS attack – “the changes applied to improve serviceability … [are] not taking as expected”.

It added that the root cause won’t be revealed until the issue has been mitigated and services returned to normal.

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