If your game is suddenly crashing and displays the following error window (see attached image), go to the directory that is mentioned and manually delete that specific pakchunk file.
This will be located in your Mordhau install directory.
Once done, head over to steam, right-click on Mordhau, go to Properties -> Local Files and click "Verify integrity of game files...".
Once completed, repeat the process one or two times to make sure that steam hasn't downloaded any corrupted files.