This content has 4 years. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

It seems, the new Visual Studio 2019 release with version 16.7 could not build the AndroidBindings projects. (For further information about what is an android binding proj, see: https://docs.microsoft.com/en-us/xamarin/android/platform/binding-java-library/)

The compiler gives the following error message:

...\MSBuild\Xamarin\Android\Xamarin.Android.Bindings.targets(327,5): warning MSB6002: The command-line for the "BindingsGenerator" task is too long. Command-lines longer than 32000 characters are likely to fail. Try reducing the length of the command-line by breaking down the call to "BindingsGenerator" into multiple calls with fewer parameters per call.

Workarounds like: Change the path of the soulution to shorter one does not seems to work.
The only solution for the problem was to downgrade VisualStudio to 16.5.4 (to the last working one for me)