Hi Mael,
Just to be clear, could you confirm the versions of the SonarQube server and SonarC# plugin you are using? (from your other
posting today I'm not sure if you are referring to the SonarC# 6.6 RC1 or SonarQube 6.6)
What is the name of the file that is causing the error, and also the name of the project that contains it?
Are you setting sonar.sources explicitly? I don't think that should be necessary for when running using the Scanner for MSBuild.
Thanks,
Duncan