Build failures with Mono 5.14.0.177, msbuild 15.0, nuget 4.7.1 on Travis CI, but not reproducible in VirtualBox

Question

I'm getting build failures with Mono 5.14.0.177, msbuild 15.0, nuget 4.7.1 on Travis CI for both Xenial and Trusty Ubuntu, but not reproducible in VirtualBox, Ubuntu Xenial.

After running:

mono tools/nuget/nuget.exe restore pythonnet.sln -o packages

the error message is:

Currently running NuGet.exe 4.1.0.
Updating NuGet.exe to 4.7.1.
Update successful.
MSBuild auto-detection: using msbuild version '15.0' from '/usr/lib/mono/msbuild/15.0/bin'.
Error parsing solution file at /home/travis/build/pythonnet/pythonnet/pythonnet.sln: Invalid Image

Here is successful build in VirtualBox:

https://gist.github.com/denfromufa/23557331aba2ad548eba2fbff84f2307

And failing build in Travis CI:

https://travis-ci.org/pythonnet/pythonnet/jobs/419381040

More details in this issue on GitHub:

https://github.com/pythonnet/pythonnet/pull/698

Answer 1

This issue has been fixed in pythonnet Travis CI temporarily by downgrading to msbuild 14.0:

cmd = "{0} update -self".format(nuget)
self.debug_print("Updating NuGet: {0}".format(cmd))
subprocess.check_call(cmd, shell=use_shell)
cmd = "{0} restore pythonnet.sln  -MSBuildVersion 14 -o packages".format(nuget)

https://github.com/pythonnet/pythonnet/blob/master/setup.py#L332