NuGet Package restore failed for project MyProject.Application: The process cannot access the file 'C:\MySolution\packages\Microsoft.Bcl.Build.1.0.21\build/Microsoft.Bcl.Build.Tasks.dll' because it is being used by another process..
Any idea how to fix this issue? Thanks.
In Windows Explorer went to the folder where the NuGet packages are installed for my solution
<VS Solution>\packages\
and deleted all the Microsoft.Bcl.* folders. After that could rebuild the solution without problems.