Microsoft is working to resolve a known issue that delays or prevents some users from opening the Microsoft Teams desktop app on Windows devices.
Microsoft listed the incident under service alert TM1466820 on Thursday at 4:45 p.m. EDT. The company advised affected customers to use Microsoft Teams on the web or the Teams mobile app as a temporary workaround.
“Specifically, when opening Microsoft Teams for the first time on a Windows device, some users may initially have trouble loading the client or may experience a loading delay of up to two minutes,” Microsoft said in its incident report.
“While we are focused on remediation, affected users may be able to work around the impact by using alternative Teams access methods, such as Microsoft Teams on the web or the Teams mobile app.”
Microsoft is analyzing service logs and telemetry data to identify the root cause of the Teams startup problem. The company has also contacted some affected customers to gather additional information and determine possible mitigation measures.
Microsoft is simultaneously investigating a separate issue affecting Microsoft Teams for Mac. The problem prevents some Mac users from joining Teams calls and meetings and is being tracked under service alert TM1466659. Microsoft confirmed the incident Thursday at 10:57 a.m. EDT.
Microsoft initially suspected that a recent code change had caused the Teams calling and conferencing infrastructure to stop processing certain requests. However, further investigation indicated that the change may not be responsible, and Microsoft is reassessing the root cause.
“Users may be unable to participate in calls or meetings in Microsoft Teams for Mac,” Microsoft said. “We are re-evaluating our understanding of the root cause and reviewing service logs to determine the cause of the impact so we can determine next steps to remediate the impact.”
In April, Microsoft resolved another known issue that prevented some Microsoft Teams Free users from chatting with or calling other users.
Microsoft also recently acknowledged a bug causing crashes and startup failures in Microsoft Teams and the new Outlook app after users installed Windows security updates released following the August 2026 Patch Tuesday updates.
Separately, Microsoft notified customers about an ongoing Exchange Online issue affecting multiple mailboxes. The problem is generating “server busy” errors and delaying emails sent to and received from external domains.
This is a developing story and will be updated as more information becomes available.
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Source: www.bleepingcomputer.com