Cannot copy multifile assembly 'assembly' to directory 'directory'. <reason>
Multifile assemblies are copied to a subdirectory of the project directory from which they will be run. For example, if the output path is c:\project1\bin, and there exists an assembly (whose CopyLocal property is true) named Test containing files a.dll and b.dll, you will have the following file structure after the copy is complete:
c:\project1\bin\Test c:\project1\bin\Test\Test.dll (main assembly) c:\project1\bin\Test\a.dll (file a.dll) c:\project1\bin\Test\b.dll (file b.dll)
This error would be displayed by the project system if the directory c:\project1\bin\Test could not be created on disk.
This error indicates that you are out of disk space or are hitting the MAX_PATH limit for path lengths.
To correct this error
Check for disk space.
Move the project to a folder whose path length is less than the path length of the folder the project is currently in.
Change the output directory to a folder with a shorter absolute path length (applicable for client projects only).