Microsoft is investigating an ongoing issue causing some Windows users to face significant delays or outright failures when launching the Microsoft Teams desktop client.
The company acknowledged the problem, tracked internally as TM1466820, and confirmed it remains unresolved as engineers continue digging through service logs to find a root cause.
According to Microsoft’s incident notice, affected users encounter trouble specifically during the first launch of Teams on a Windows device. Some cannot load the client at all, while others experience delays stretching up to two minutes before the app becomes usable.
For an application many organizations rely on for daily communication, even a two-minute hang at startup can disrupt morning routines, delay meeting joins, and frustrate employees trying to check urgent messages.
Microsoft has classified the issue’s scope as affecting “some users” within impacted organizations, particularly those opening Teams to view new messages. The company noted that impact varies across tenants, meaning not every organization or every user within an affected organization will necessarily notice the slowdown.
While a permanent fix is being developed, Microsoft has recommended workarounds to keep productivity moving. Affected users can switch to Microsoft Teams on the web through a browser, or use the Teams mobile app, both of which reportedly remain unaffected by the desktop client’s loading problem. These alternatives don’t fix the underlying issue but let employees stay connected until Microsoft rolls out a resolution.
In its most recent update, posted at 8:41 AM on September 4, 2026, Microsoft said its analysis of service logs and telemetry data has so far been “inconclusive.” Engineers have not yet pinpointed why the desktop client is struggling to load on some Windows machines.
Microsoft Teams Desktop Client Fails
To move the investigation forward, Microsoft is reaching out directly to a subset of impacted users, requesting client-side logs from their devices. The company expects these logs will help isolate the underlying trigger and clarify what remediation options are viable.
This is not the only Teams-related disruption Microsoft has grappled with recently. Earlier in the year, a regression in the Teams client’s build-caching system caused similar launch failures, which Microsoft resolved by reverting a faulty service update.
Separately, Windows 11 users on ARM-based devices, such as Surface Pro and Surface Laptop models, have faced Teams and Outlook launch failures tied to an August security update, an issue Microsoft has since mitigated through a Microsoft Store update.
For now, IT administrators managing Windows fleets should monitor the Microsoft 365 admin center’s service health dashboard for updates on TM1466820 and consider proactively informing staff about the web and mobile workarounds.
Microsoft has not provided an estimated resolution timeline, but its outreach for client logs suggests the investigation is entering a more targeted, evidence-gathering phase rather than a quick patch rollout.
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