After applying PyQt5 Upgrade PR, in Windows 10, if you press the REPL button in Python mode, you can see the error below:

[roboticsware]

          In Windows 10, if you press the REPL button in Python mode, you can see the error below:

2025-02-13 15:04:14,915 - traitlets:653(_create_connected_socket) DEBUG: Connecting to: tcp://127.0.0.1:62730
2025-02-13 15:04:14,931 - root:175(excepthook) ERROR: Unrecoverable error
Traceback (most recent call last):
  File "C:\Users\user\AppData\Local\Programs\Mu Editor Custom\Python\lib\site-packages\mu\modes\python3.py", line 372, in on_kernel_start
    self.view.add_jupyter_repl(kernel_manager, kernel_client)
  File "C:\Users\user\AppData\Local\Programs\Mu Editor Custom\Python\lib\site-packages\mu\interface\main.py", line 716, in add_jupyter_repl
    kernel_manager.kernel.gui = "qt4"
AttributeError: 'NoneType' object has no attribute 'gui'

Originally posted by @JeongJun-Lee in #2487 (comment)