Microsoft says an ongoing incident is preventing users of its Teams collaboration platform and Office for the web cloud-based productivity suite from opening files.

"We're investigating reports that some users are unable to open files in Office for the web or Microsoft Teams," the company's Microsoft 365 Status tweeted earlier.

According to further information shared in the admin center under MO1329446, this issue impacts multiple Office Apps, including Microsoft Excel for the web.

"Users may be unable to open files in Office for the web. Impacted Office Apps include, but are not limited to Excel, PowerPoint," Microsoft added. "When users open documents, impacted users are shown the following the following error message' Office Online services aren't available right now. We're working to restore all services as soon as possible."

While it hasn't specified which regions are affected or provided a final timeline for full remediation, the company says it's currently investigating service telemetry to isolate the root cause of the issue.

In a subsequent update, the company revealed that "initial analysis indicates a potential cross-service issue impacting Office for the web experiences."

Microsoft has also tagged this ongoing outage as an incident, a term commonly used for critical service issues involving noticeable user impact.

Earlier today, Microsoft addressed another incident that blocked customers from setting up multi-factor authentication (MFA) on some accounts or from accessing the MySignIn service.

The company blamed the platform access issues on a recent cache configuration change that required a failover, triggering high CPU and memory utilization as traffic from European Union customers began to peak.

In April, Microsoft also fixed a known issue caused by a recently deployed backend change that blocked some Microsoft Teams Free users from chatting and calling others, as well as a bug introduced by a Microsoft Edge browser update that prevented Windows users from joining Teams meetings.

The same month, it reverted a recent service update that had blocked some Teams users from launching the desktop client, leaving them stuck on the loading screen with a "We're having trouble loading your message. Try refreshing." error.

Update June 01, 13:36 EDT: Microsoft says the issue has been resolved.

"We've confirmed through customer reports and service telemetry that the impact has been resolved, and the service has remained stable for an extended period of time," the company said in an advisory center update.

"As the issue recovered without any specific engineering actions being implemented, engineer teams continue to investigate the underlying root cause so actions can be taken to prevent the issue from reoccurring."