Build Project with MSBuild programmatically - NuGetSdkResolver or InvalidProjectFileException error

Question

I want to build a tool which is capable of building C# projects.
For that I did the following thing:

            var buildOutput = new List<string>();
            var buildError = new List<string>();
            var buildProcess = new Process
            {
                StartInfo = new ProcessStartInfo
                {
                    FileName = "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Professional\\MSBuild\\Current\\Bin\\MSBuild.exe",
                    Arguments = path + " /t:Rebuild /p:Configuration=Debug",
                    UseShellExecute = false,
                    RedirectStandardOutput = true,
                    RedirectStandardError = true,
                    CreateNoWindow = true
                }
            };

            buildProcess.Start();
            while (!buildProcess.StandardOutput.EndOfStream)
            {
                buildOutput.Add(buildProcess.StandardOutput.ReadLine());
            }
            while (!buildProcess.StandardError.EndOfStream)
            {
                buildError.Add(buildProcess.StandardError.ReadLine());
            }

The path of the MSBuild.exe is hardcoded now, so I can be really sure it is the right one. The code runs through but the output is this:

error MSB4244: The SDK resolver assembly "C:\Program Files\dotnet\sdk\3.1.408\Microsoft.Build.NuGetSdkResolver.dll" could not be loaded. The file or assembly "Microsoft.Build.NuGetSdkResolver, Version=5.7.1.7, Culture=neutral, PublicKeyToken=31bf3856ad364e35" or a dependency of it was not found. An attempt was made to load a file with an incorrect format.

When I look into the path, the .dll file exists but in a wrong version (Version 5.7.1.4). The thing here is, when I call the MSBuild.exe with the same project over the commandprompt it works fine.

So my approach was to try something else:

    List<ILogger> loggers = new List<ILogger>
            {
                new FileLogger
                {
                    Parameters = Path.GetTempFileName()
                }
            };

    var globalProperties = new Dictionary<string, string>
    {
        { "Configuration", configuration }
    };

    var project = new Project(path, globalProperties, "Current");

    var result = project.Build("Build", loggers);
    return result;

This code works fine but only for .netCore projects. When I try it with a .net ramework project I get the following error

Microsoft.Build.Exceptions.InvalidProjectFileException: 'The imported project "C:\Program Files\dotnet\sdk\3.1.408\Microsoft\VisualStudio\v16.0\WebApplications\Microsoft.WebApplication.targets" was not found. Make sure that the expression in the import declaration "C:\Program Files\dotnet\sdk\3.1.408\Microsoft\VisualStudio\v16.0\WebApplications\Microsoft.WebApplication.targets" is correct and that the file exists on the disk.

Maybe some of you can help me with one of my solutions.

Answer 1

I ran into this problem. It was traced to having MsBuild.dll already loaded in the parent process (in my case, due to using MsBuildLocator). This was evidenced by running msbuild.exe with detailed logging enabled (-v:d) and observing that the SDK version of the msbuild engine was still being used internally, rather than the msbuild.exe version. For example:

Build started 4/18/2022 10:47:50 AM.
Process = "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\MSBuild\Current\Bin\MSBuild.exe"
MSBuild executable path = "C:\Program Files\dotnet\sdk\5.0.407\MSBuild.dll"
Command line arguments = ""C:\Program Files\Microsoft Visual Studio\2022\Enterprise\MSBuild\Current\Bin\MSBuild.exe" "C:\MyNetFrameworkSolution.sln" -v:d"

The problem was fixed by specifying the environment variable MSBUILD_EXE_PATH in ProcessStartInfo. Ie., something to the effect of:

string msBuildPath = @"C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\MSBuild\Current\Bin";
processStartInfo.EnvironmentVariables[@"MSBUILD_EXE_PATH"] = msbuildPath;

After this change, the logs should show that MSBuild executable path = the same as your Process =, which is msbuild.exe.