That, on its own, is a very un-PyInstaller looking type of error. It’s more likely that either your built app is reading a different xml file or that you are filtering self.text in a way that depends on the existence of 7z.exe. Are you able to reduce it down to something that you can send us? It looks like your reading and xml then looking up an entry in it? Is self.text is the direct contents of the parsed xml? Can you at least share the snippet of Python code that opens/locates the xml? Also check that running Python from terminal works - python xpgroundworks.py - your IDE sandboxes things which can make PyInstaller look like the culprit when it isn’t.