Cannot able to share screen inside the Azure Virtual Desktop in Teams application

For Teams screen sharing in Azure Virtual Desktop with SlimCore, the most relevant checks are these:

1. Restart the Teams client once.
   • Teams requires one restart to transition from WebRTC to SlimCore when the plugin is first detected.
   • If tenant switching happened recently, restarting Teams can also mitigate screen sharing rendering issues.
2. Confirm the session is actually using SlimCore and not fallback mode.
   • If Teams shows "Azure Virtual Desktop SlimCore Media Not Connected", screen sharing can fail because media is falling back to server-side rendering.
   • If Teams shows "Azure Virtual Desktop Media Optimized" instead of SlimCore, check whether the endpoint plugin is loaded.
3. Verify the AVD plugin is loaded on the endpoint.
   • Use Process Explorer.
   • Enable the bottom pane and switch to the DLL tab.
   • Check the msrdc.exe process and confirm MsTeamsPluginAvd.dll is loaded.
   • If the plugin is detected for the first time, restart Teams again.
4. Check Event Viewer on the session host VM.
   • For Teams 24123.X.X.X or later, review Microsoft Teams VDI-related errors.
   • This is specifically recommended when SlimCore optimization is not working as expected.
5. If Screen Capture Protection is enabled, verify supported versions.
   • With AVD Screen Capture Protection enabled to block screen capture on the client, Teams sharing works only with these minimum versions:
     • Teams 25060.205.3499.6849
     • Remote Desktop client 1.2.6081 or Windows App 2.0.379
   • On lower versions, shared content can appear as a black screen.
6. If using full monitor sharing, test app sharing instead.
   • In full monitor sharing, the Teams call monitor is visible to other participants, but video elements inside it appear as blank squares.
   • App sharing shows only the shared application and does not capture the call monitor.
7. If using RemoteApp, verify content sharing prerequisites.
   • For classic Teams on Azure Virtual Desktop, content sharing requires:
     • WebRTC Redirector Service 1.31.2211.15001 or later
     • Windows Desktop client 1.2.3401 or later
   • The session host VM must have the registry value ShareClientDesktop=1 under:
     • HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\AddIns\WebRTC Redirector\Policy
   • Warning: registry changes can affect sharing behavior for all users on that session host. Apply carefully and validate on a test host first.
8. Check for known screen-sharing limitations.
   • In Azure Virtual Desktop, redirected videos during screen sharing and application window sharing aren't supported.
   • If sharing admin windows such as Task Manager, participants can see a black area where the presenter toolbar or call monitor is located.

If the symptom is specifically "sharing starts, but the other participant cannot see the shared content," the highest-value checks are:

• confirm Teams is not in SlimCore Media Not Connected mode,
• confirm MsTeamsPluginAvd.dll is loaded in msrdc.exe,
• restart Teams after plugin detection,
• check whether Screen Capture Protection is enabled with unsupported versions,
• test app sharing instead of full monitor sharing.

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