Don't let dotnet CLI disable MSBUILDUSESERVER - #54918
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…UILD_SERVER is unset Previously the CLI unconditionally wrote MSBUILDUSESERVER to "1" or "0" based solely on DOTNET_CLI_USE_MSBUILD_SERVER. When that variable was unset (the default), the host wrote MSBUILDUSESERVER=0, clobbering any value the user had set directly via MSBUILDUSESERVER and forcing the MSBuild server off. Now the CLI only sets MSBUILDUSESERVER=1 when DOTNET_CLI_USE_MSBUILD_SERVER opts in, and otherwise leaves the variable untouched. This lets either variable toggle the MSBuild server on, so a user-provided MSBUILDUSESERVER=1 is honored. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
baronfel
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Jun 22, 2026
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Pull request overview
This PR updates the dotnet CLI’s MSBuild forwarding behavior so it no longer disables the MSBuild server by overwriting MSBUILDUSESERVER=0 when DOTNET_CLI_USE_MSBUILD_SERVER is not set, thereby honoring a user-provided MSBUILDUSESERVER value.
Changes:
- Stop unconditionally setting
MSBUILDUSESERVERto"0"whenDOTNET_CLI_USE_MSBUILD_SERVERis unset/false. - Only set
MSBUILDUSESERVER=1whenDOTNET_CLI_USE_MSBUILD_SERVERopts in.
JanProvaznik
approved these changes
Jun 22, 2026
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/backport to release/10.0.4xx |
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Started backporting to |
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Don't let dotnet CLI disable MSBUILDUSESERVER when DOTNET_CLI_USE_MSBUILD_SERVER is unset
Previously the CLI unconditionally wrote MSBUILDUSESERVER to "1" or "0" based solely on DOTNET_CLI_USE_MSBUILD_SERVER. When that variable was unset (the default), the host wrote MSBUILDUSESERVER=0, clobbering any value the user had set directly via MSBUILDUSESERVER and forcing the MSBuild server off.
Now the CLI only sets MSBUILDUSESERVER=1 when DOTNET_CLI_USE_MSBUILD_SERVER opts in, and otherwise leaves the variable untouched. This lets either variable toggle the MSBuild server on, so a user-provided MSBUILDUSESERVER=1 is honored.