This is Bug 1967402 opened against Fedora 34, which is EOF so the bug was closed. Bug still exists in Fedora 37. Original report reads as follows: PyQt5 applications print out "QSocketNotifier: Can only be used with threads started with QThread" when executed. Version-Release number of selected component (if applicable): 5.15.0-8.fc34 How reproducible: Always happens on my system. Steps to Reproduce: Execute the following Python code. import sys from PyQt5.QtWidgets import QApplication, QLabel app = QApplication(sys.argv) label = QLabel('Hello World!') label.show() sys.exit(app.exec()) Actual results: The terminal shows "QSocketNotifier: Can only be used with threads started with QThread" when the program starts. Expected results: Nothing should be printed. I also see the problem using import matplotlib.pyplot as plt fig, ax = plt.subplots() This is part of a larger program that then does not show a graphic. Note that I am using Wayland.
I also have this bug on frdora 38 And i get this result in terminal: QSocketNotifier: Can only be used with threads started with QThread qt.qpa.qgnomeplatform.theme: The desktop style for QtQuick Controls 2 applications is not available on the system (qqc2-desktop-style). The application may look broken.