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Run npx skillmds@latest add dotnet/use-bootstrap-msbuild in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Use Bootstrap Msbuild free to use?

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Who published Use Bootstrap Msbuild?

.NET (Microsoft) (@dotnet) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Use Bootstrap Msbuild by dotnet — Agent Skill

Name: Use Bootstrap Msbuild
Author: .NET (Microsoft)

File contents

Testing Bug Reproductions with Bootstrap MSBuild

This skill guides you through testing a bug reproduction project against your locally-built MSBuild to verify a fix.

Overview

After making changes to MSBuild, you need to test them against a repro project. The "bootstrap" is a self-contained MSBuild installation built from your local changes. It includes all dependencies needed to build real projects.

Step 1: Build MSBuild with Bootstrap

Build MSBuild to create the bootstrap directory:

# Windows
.\build.cmd

# Unix/macOS
./build.sh

This creates the bootstrap at artifacts\bin\bootstrap\ with your changes.

Rerun this after making any code change. If run in the default mode, there may be some errors on subsequent builds about locked files (due to MSBuild worker node processes lingering). If so, run ./artifacts/bin/bootstrap/core/dotnet build-server shutdown.

Step 2: Run Your Repro Project

.NET Core / .NET SDK Projects

Use the bootstrap dotnet CLI directly (preferred):

# Windows
artifacts\bin\bootstrap\core\dotnet.exe build <path-to-repro.csproj>

# Unix/macOS
./artifacts/bin/bootstrap/core/dotnet build <path-to-repro.csproj>

All of the usual command line arguments should work, including -bl to create binlogs.

.NET Framework Projects

If the problem is specific to the .NET Framework MSBuild.exe that is used in Visual Studio, and you're running on Windows, you can use the bootstrap MSBuild.exe directly:

artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <path-to-repro.csproj>

Note: The .NET Framework bootstrap output will only be complete when built on Windows using MSBuild.exe.

Changes not reflected

Verify bootstrap was rebuilt: check artifacts\bin\bootstrap\core\sdk\*\MSBuild.dll timestamp

Kill any lingering MSBuild server processes:

./artifacts/bin/bootstrap/core/dotnet build-server shutdown
# Or use the helper function after sourcing msbuild-build-env.ps1
killdotnet

Repro works with bootstrap but not with installed MSBuild

Your fix is working! The repro uses your local changes while the installed MSBuild has the bug.

Quick Reference

Scenario	Command
Build bootstrap	`.\build.cmd`
.NET Core repro	`artifacts\bin\bootstrap\core\dotnet.exe build <project>`
.NET Framework repro	`artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <project>`

---name: use-bootstrap-msbuilddescription: Guide for testing bug reproductions against locally-built MSBuild. Use this when you have a repro project and want to verify a fix works before submitting a PR.---# Testing Bug Reproductions with Bootstrap MSBuildThis skill guides you through testing a bug reproduction project against your locally-built MSBuild to verify a fix.## OverviewAfter making changes to MSBuild, you need to test them against a repro project. The "bootstrap" is a self-contained MSBuild installation built from your local changes. It includes all dependencies needed to build real projects.## Step 1: Build MSBuild with BootstrapBuild MSBuild to create the bootstrap directory:```powershell# Windows.\build.cmd# Unix/macOS./build.sh```This creates the bootstrap at `artifacts\bin\bootstrap\` with your changes.Rerun this after making any code change. If run in the default mode, there may be some errors on subsequent builds about locked files (due to MSBuild worker node processes lingering). If so, run `./artifacts/bin/bootstrap/core/dotnet build-server shutdown`.## Step 2: Run Your Repro Project### .NET Core / .NET SDK ProjectsUse the bootstrap `dotnet` CLI directly (preferred):```powershell# Windowsartifacts\bin\bootstrap\core\dotnet.exe build <path-to-repro.csproj>``````bash# Unix/macOS./artifacts/bin/bootstrap/core/dotnet build <path-to-repro.csproj>```All of the usual command line arguments should work, including `-bl` to create binlogs.### .NET Framework ProjectsIf the problem is specific to the .NET Framework `MSBuild.exe` that is used in Visual Studio, and you're running on Windows, you can use the bootstrap MSBuild.exe directly:```powershellartifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <path-to-repro.csproj>```**Note**: The .NET Framework bootstrap output will only be complete when built on Windows using `MSBuild.exe`.### Changes not reflected1. Verify bootstrap was rebuilt: check `artifacts\bin\bootstrap\core\sdk\*\MSBuild.dll` timestamp2. Kill any lingering MSBuild server processes: ```powershell ./artifacts/bin/bootstrap/core/dotnet build-server shutdown # Or use the helper function after sourcing msbuild-build-env.ps1 killdotnet ```### Repro works with bootstrap but not with installed MSBuildYour fix is working! The repro uses your local changes while the installed MSBuild has the bug.## Quick Reference| Scenario | Command ||----------|---------|| Build bootstrap | `.\build.cmd` || .NET Core repro | `artifacts\bin\bootstrap\core\dotnet.exe build <project>` || .NET Framework repro | `artifacts\bin\bootstrap\net472\MSBuild\Current\Bin\MSBuild.exe <project>` |## See Also- [Bootstrap Documentation](https://github.com/dotnet/msbuild/blob/main/documentation/wiki/Bootstrap.md)- [Building and Debugging Guide](https://github.com/dotnet/msbuild/blob/main/documentation/wiki/Building-Testing-and-Debugging-on-Full-Framework-MSBuild.md)

Frequently asked questions

Use Bootstrap Msbuild