Visual Studio "Could not copy" .... during build

It's because you have closed your application, but it's still running in background.

Temporary solution:

• Go to Task Manager (Ctrl + Shift + Esc).
• Go to Processes tab and find "YourProjectName.exe".
• Check "Show processes from all users" if you can't find your process.
• End Process it.

Permanent solution: you have to close your application through coding. Here is the code...

System.Windows.Forms.Application.Exit();

You have to put this code in to the form's closing event in all form. Example:

private void frm_menu_FormClosing(object sender, FormClosingEventArgs e)
{
    System.Windows.Forms.Application.Exit();
}

I have encountered similar error messages in Visual Studio 2013.

Mostly, I have found that this situation has occurred when a debug process was halted because of an exception.

When clean+build has not resolved this problem for me, I have had success by doing the following:

• Closing Visual Studio
• Deleting the bin and obj folders, and
• Reopening Visual Studio.

This "bug" has existed since Visual Studio 2003.

Finally, I have also found that I can often overcome this problem by simply renaming the executable file and then deleting it.

In Visual Studio Premium 2013 (Update 3), I solved this with a pre-build one-liner:

(if exist "$(TargetDir)*old.pdb" del "$(TargetDir)*old.pdb") & (if exist "$(TargetDir)*.pdb" ren "$(TargetDir)*.pdb" *.old.pdb)

This gracefully deletes any old PDB files (if it can), then renames anything that's left with a .old.pdb extension. A nice side effect is that if the old PDB is still locked, it just adds another .old piece to the filename, and they all get cleaned up next time you restart Visual Studio and do a build.

For example, build/debug session 1 leaves MyProject.pdb locked.
The next time you build:
MyProject.pdb --> MyProject.old.pdb

Then, build/debug session 2 is started, and both MyProject.pdb and MyProject.old.pdb are still locked:
MyProject.old.pdb --> MyProject.old.old.pdb
MyProject.pdb --> MyProject.old.pdb

Finally, restarting Visual Studio and doing a fresh build will get rid of both of these, and continue the process as usual.

the .vhost.exe is a debugger process, so it appears that the process being debugged hasn't closed properly. Chances are you have a bug that's keeping it alive and are not stopping the debug process correctly - there are options to detach from the process when you click 'stop debugging' instead of actually killing the debugger so maybe you have that set.

But that's the problem - the file you're trying to copy over is locked (ie still being used) by the OS so its preventing the copy. Ensure that file is free and you'll be able to copy.