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MSTSC.EXE hangs when copying large files via \\TSCLIENT

Stéphane BARIZIEN 16 Reputation points
2022-09-03T11:48:35.897+00:00

(redirected from https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/mstscexe-hangs-when-copying-large-files-via/6b4ac51d-5826-44dd-9d31-8495e23a2cbe)

I'm facing a rather weird issue between two of my Windows 10 systems.

From machine A (running Windows 10.0.19044.1889.amd64fre.vb_release.191206-1406) I RD to machine B (running Windows 10.0.19044.1889.amd64fre.vb_release.191206-1406) using MSTSC.EXE, the built-in Remote Desktop client (file version 10.0.19041.1 (WinBuild.160101.0800)).

Over that RD connection, I run PowerShell 7.2.6, and run a script that copies files between the two machines using ROBOCOPY via the \TSCLIENT\C pseudo-share.

If said copying process involves "large" files (last occurrence: one 384MB file), MSTSC hangs.

I have to close it, launch a RD session using MobaXterm, from which the ROBOCOPY operation typically resumes that's to ROBOCOPY's retry mechanism.

Any clue as to how I can troubleshoot / diagnose this?

Windows for business | Windows Client for IT Pros | User experience | Remote desktop services and terminal services
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  1. resistor 6 Reputation points
    2025-10-02T12:27:30.1133333+00:00

    Hello!
    I realize that this reply is quite late, but perhaps this information might still be useful for someone.

    In my case, the exact situation was resolved by disabling UDP protocol for RDP on the client side.

    • Via group policy:
      Computer Configuration\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Connection Client\
      policy setting Turn Off UDP on Client or
    • Via registry:
      key HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\Client,
      value fClientDisableUDP,
      type REG_DWORD,
      value 1
    1 person found this answer helpful.
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  2. Stéphane BARIZIEN 16 Reputation points
    2025-11-02T09:17:01.24+00:00

    Hi,

    Thanks for your response -- which came so late I had even forgotten I'd asked the question eons ago... I found the response by asking Copilot about my issue 😉

    This indeed fixes the issue (as far as I can tell with today's file copy session).

    Are there official Microsoft articles about this?

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