KDevelop 5.3.0-x64 With a python project opened (doesn't crash with a Qt graphical project), pressing in Project | Open Configuration, to try to change de default python interpreter, crashes probably because an antivirus (Cb Defense) thinks Kdevelop opening cmd.exe is a threat. (Can't test without antivirus). Didn't crashed with Kdevelop 5.2.4-x64
There was a bug in 5.3.0 where the project settings dialog would crash for a "Generic" project (not using a supported buildsystem). This would apply to most Python projects, but not the Qt example. Fixed in 5.3.1. (please comment if there was a specific reason you suspected antivirus to be involved). *** This bug has been marked as a duplicate of bug 400769 ***