How to debug a project file in MSBuild 12.0 / VS2013? has an answer, but apparently that method is not supported in Visual Studio 2015/MSBuild 14. Does anyone know a way to perform MSBuild debugging in Visual Studio 2015/MSBuild 14? Bonus points for scoop about Visual Studio 2017.
The MSBuild debugger was never officially supported and was cut from MSBuild in favor of cross-platform support in the VS 2015/MSBuild 14 timeframe.
There are many ways to debug the behavior of a build. The combination of a Verbosity=Diagnostic
build log and the preprocessed project (msbuild /pp:preprocessed.xml path\to\the.csproj
creates a file containing all of the build logic for a given project) is extremely powerful. You may also be interested in the UI that the MSBuildStructuredLog provides, which helps pare down the massive output produced by a diagnostic log.