Troubleshooting "DotVVM.Compiler.exe not found in the project" Error

If you open a DotVVM project in Visual Studio, sometimes you can see the yellow bar with the following error message:

'DotVVM.Compiler.exe' not found in the project YourProjectName!

Also, IntelliSense in DOTHTML files is broken, the directives are being underlined etc.

Visual Studio uses the DotVVM Compiler to read the settings in the DotvvmStartup file, or to precompile the DOTVVM views.

How To Resolve the Issue

The most common reason for this behavior is that Visual Studio cannot find the DotVVM binaries, because they are not present in the packages folder.

You can resolve this simply by building the solution. In the default settings, the Visual Studio runs the NuGet package restore before the build, and this operation downloads missing NuGet packages. The DotVVM package contains the DotVVM Compiler binary.

If the package restore doesn't help, you can look at the Output window in the Visual Studio. If you display the output from DotVVM, you'll see the exception the compiler has returned, and the stack trace. Maybe you can figure out what's wrong from the exception - it can be caused by something you have used in the DotvvmStartup.cs. Please, keep in mind, that the DotVVM for Visual Studio has to actually execute the DotvvmStartup.cs to be able to retrieve the configuration data.