Simple to reproduce, simply click build and run, then choose your target folder, do not build as debug, choose a scene as the default scene, normal build stuff, and the build produces the exe but also this error:
Nada clue why
Additionaly, MySQL is still not supported in builds but works in editor…
Needs to go back in the oven some more for fixes.
For reference, this usually happens if you have built before, and you still have a file open of that build. Unity fails to overwrite the data directory because Windows doesn’t allow write access/overwriting files which are still in use by any other application.