PySide6.1 not compatible with matplotlib 3.4

Question

When I only install PySide6, the GUI program works well, but once I have installed matplotlib with its dependency packages(including pyqt5), then the GUI program won't work and output the error message below

This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

The problem won't be resolved even after uninstalling matplotlib again, in addition, the matplotlib is even not imported in my program.

• Python version: 3.9.4
• PySide6 version: 6.1
• matplotlib: 3.4.2
• pyqt: 5.12.3

In addition, PySide6 is installed via pip and matplotlib is installed via conda.

Answer 1

Reviewing the source code and not knowing an official announcement I can point out that at the time of writing this post matplotlib does not support any Qt6 backend so PySide6 will not be used.

Reviewing this pull request I see that they are working on incorporating it so that Qt6 will probably already be supported in future releases.