The disruption began shortly before 1.00 p.m. and affected Microsoft 365 services, Outlook and Teams. At the time, around 130,000 users had reported problems with Outlook.
Downdetector also recorded reports of service disruptions involving Amazon Web Services (AWS) and Google.
A Microsoft spokesperson confirmed that the company was investigating reports of problems affecting Microsoft 365, particularly its Exchange Online service.
“We are aware and investigating reports of users experiencing issues with Microsoft 365 services, primarily issues with Exchange Online,” the spokesperson said in a statement to CNBC, adding that the company was working to restore services as quickly as possible.
Microsoft provided updates through its Microsoft 365 Status account on X.
The company initially attributed the connectivity problems to unusually high infrastructure loads across multiple regions. It later identified the cause as several servers becoming unexpectedly unavailable, placing additional pressure on the remaining infrastructure. Some servers were also failing automated health checks.
In an update posted at around 4.00 p.m., Microsoft said it had validated an alternative service health-check method, allowing some affected servers to return online.
The company said it was expanding the solution across its infrastructure while preparing automated recovery systems to identify and restart unresponsive servers.
Microsoft also said it had taken steps to prevent additional servers from being affected while efforts continued to restore the disrupted systems.
Meanwhile, Amazon Web Services said its services were operating normally and described reports linking it to the disruption as inaccurate. The company directed users to its service health dashboard for verified updates.
