I've got this error while compiling a big c# solution in Visual Studio 2010. Each time after compilation I had to delete obj folder of one the projects used by this solution. Otherwise I got the following error:
Could not write to output file '...\obj\Debug\Foo.Bar.dll' The process cannot access the file because it is being used by another process
I've was looking for a solution all over the Internet and actually found/tried few of them.
For example : a lot of people on dev forums were suggesting not to start the compilation while UserControl (in some other sources From) designer is opened.
Some other people used pre-build scripts for obj folder removal, this particular solution is acceptable, but if the issued project is a widely used library its recompilation will cause recompilation of "parent" projects.
Finally I've discovered a solution for this VS2010 (SP1 too) "bug" and I want to share it with stackoverflow users.
In my case the problem was that csproj file was SELF-REFERENCING the locked
'...\obj\Debug\Foo.Bar.dll' file. Crazy I know. So I solved this annoying issue by removing the following line from
<Reference Include="Foo.Bar"> <HintPath>obj\Debug\Foo.Bar.dll</HintPath> </Reference>