Teams Desktop Client Update: Windows MC1189656 Changes

Message ID: MC1189656 (Updated)

Updated November 25, 2025: We have updated the content below to show as intended. Thank you for your feedback.

[Introduction]

We’re improving the performance and startup time of calling features in the Microsoft Teams Desktop Client for Windows. To achieve this, we’re introducing a new child process named ms-teams_modulehost.exe that will handle the calling stack separately from the main application process (ms-teams.exe). This change optimizes resource usage and enhances meeting experiences.

[When this will happen:]

Worldwide, GCC, GCC High, and DoD: Rollout will begin early January 2026 and complete by late January 2026.

Note: Timelines may shift due to year-end feature flag rollout freeze.

[How this affects your organization:]

Who is affected: All users running the Teams Desktop Client on Windows.
What will happen:
- A new process (ms-teams_modulehost.exe) will appear in Task Manager under the main Teams process (ms-teams.exe).
- This process is dedicated to calling features and improves performance.
- No changes to user workflows or UI; however, admins should ensure endpoint and security software allow this new process.

[What you can do to prepare:]

Update endpoint management and security software to allowlist ms-teams_modulehost.exe alongside ms-teams.exe.
Communicate this change to helpdesk staff to avoid confusion during troubleshooting.
Update internal documentation if you reference Teams process names.

[Compliance considerations:]

No compliance considerations identified, review as appropriate for your organization.

Source: Microsoft

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