Could not load file or assembly 'xxx.Data' The process cannot access the file because it is being used by another process

Question

I have this error since today in a project which I have worked for months and has always worked.

I tried cleaning the solution and rebuild, and building works perfect. I

Answer 1

As the message says, the file is in use. This isn't a Visual Studio or .NET thing, it is an operating system thing.

Another program is using the file, that can be a virus scanner, another application that is running, or even Visual Studio (sometimes the debugger keeps a file locked).

Windows tells you what program is responsible for the lock when you try to delete or rename the file. I would recommend to do that to see what program is locking your file.