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Vincent_Duvernet's avatar
Vincent_Duvernet
Copper Contributor
Mar 25, 2026

dcdiag crash with incorrect /s parameter

Hello,

I find a mistake in my script which cause DCDiag to crash :

dcdiag /v /c /d /e /s:%computername% > C:\Temp\dcdiag.txt

 

%computername% is the mistake. I replaced it by the real server name.

Seems like input it not enough checked.

Vincent

Active Directory
windows server

1 Reply

  • kyazaferr's avatar
    kyazaferr
    MCT
    Mar 31, 2026

    The issue is caused by using %computername% incorrectly with the /s parameter. The /s parameter expects a specific Domain Controller name (FQDN or NetBIOS), not a variable that may not resolve correctly in that execution context.

     

    When %computername% does not resolve properly (for example in scheduled tasks, different shells, or remote execution), dcdiag may fail or crash because it cannot validate the target DC.

     

    Solution:

     

    Use a valid and resolvable Domain Controller name instead of %computername%, for example:

     

    dcdiag /v /c /d /e /s:DC01.contoso.local > C:\Temp\dcdiag.txt

     

    Alternatively, if you want to dynamically use the local machine name safely, use PowerShell instead of environment variables:

     

    $dc = $env:COMPUTERNAME

    dcdiag /v /c /d /e /s:$dc > C:\Temp\dcdiag.txt

     

    Or simply run without /s if you are executing the command locally on a Domain Controller:

     

    dcdiag /v /c /d /e > C:\Temp\dcdiag.txt

     

    Summary:

    /s parameter requires a properly resolvable DC name. Using %computername% can lead to failures depending on the execution context, so it’s safer to use a fixed DC name or PowerShell-based resolution.