"Specifically, when first opening Microsoft Teams on Windows devices, some users may be initially unable to load the client or may encounter loading delays of up to two minutes," Microsoft said.
Windows desktop client: loading delays and blocked launches
Microsoft has acknowledged a known issue that is delaying — and in some cases blocking — the initial launch of the Microsoft Teams desktop client on Windows systems. According to the company, the problem appears at first open: affected users may be unable to load the client or see loading delays lasting as long as two minutes. Microsoft characterized the condition as a service problem it is actively working to resolve.
Mac users unable to join calls: TM1466659 and a reassessed root cause
Separately, Microsoft confirmed an ongoing problem that prevents some Mac users from joining Teams calls and meetings. The incident is being tracked internally as TM1466659 and was confirmed on Thursday at 10:57 EDT. Microsoft initially blamed a code change that caused the Teams call and meeting service infrastructure to fail to process some requests, but after further review the company is reassessing that root-cause conclusion and has said the code change "may not be the cause of the impact."
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See what we buildInvestigation steps: telemetry, service logs, and user outreach
Microsoft said it is still analyzing service logs and telemetry to isolate the source of both sets of problems. The company has reached out to some affected users to gather additional data needed to determine mitigation options. While remediation work continues, Microsoft advised that affected users may be able to avoid impact by using Microsoft Teams on the web or alternative access methods such as the Teams mobile app.
Related Microsoft service problems reported this week
The Teams desktop and Mac-call issues arrive alongside other, recent Microsoft service incidents. In April, Microsoft resolved a known issue that had blocked some Microsoft Teams Free users from chatting and calling others. On Tuesday, the company confirmed a separate bug that caused crashes and launch failures for Microsoft Teams and New Outlook users after installing Windows security updates released since the August 2026 Patch Tuesday. Earlier today Microsoft also notified customers of an ongoing Exchange Online issue affecting multiple mailboxes that is triggering "Server busy" errors and delaying email sent to and received from external domains.
How technologists, affected enterprises, and end users are responding
- Technologists and security teams: are likely focusing on collecting and correlating telemetry and service logs as Microsoft has requested, and on testing access alternatives such as the web client and mobile apps while root-cause analysis continues.
- Affected enterprises and procurement leaders: will be monitoring Microsoft’s remediation status, communicating temporary access options to employees, and tracking the Exchange Online “Server busy” delays that may affect external email flows.
- End users: are being steered to Teams on the web or the mobile app to avoid the reported launch and call-join failures; Mac users unable to join meetings remain affected while Microsoft reassesses the cause and determines next remediation steps.
Microsoft’s public updates make clear that the incidents are under active investigation and that the company is both collecting telemetry and contacting impacted users to identify fixes. With the company reassessing the Mac-call root cause and continuing remediation work on the Windows launch problem, the situation remains dynamic and Microsoft has labeled the events a developing story.
