PySide6 does not work with Anaconda

[Johan_R]

@JonB said in PySide6 does not work with Anaconda:

https://github.com/ContinuumIO/anaconda-issues/issues/1270

Thanks for taking the time too look into this. I tried some of the remedies proposed in that thread but with no success so far. I do not think it is the same issue. That thread deals with the situation that the platform plugins are not found at all. The thread does not mention metadata at all. In my case they are found but the metadata is somehow invalid which suggests that something else has gone wrong earlier.

[JonB]

@Johan_R
You may well be right. The idea was to read to figure what gets what from where.

This is my last wild suggestion, because obviously I don't know. You say it works outside anaconda but not inside anaconda. Presumably those anaconda3/Library/plugins/platforms/q*.dll exist somewhere else not inside the anaconda area? Assuming so: compare some of the files. I suppose they are different? Are the anaconda ones the same architecture, I'm thinking they need to be 64-bit not 32-bit? What if you temporarily make yours use the non-anaconda ones, either by some PATH or whatever manipulation, or just by temporarily copying/renaming so that directory contains non-anaconda ones? Just an idea, to try to diagnose....

[Johan_R]

I tried with MIniconda instead of Anaconda.
(Miniconda is minimal conda version. It includes only conda, Python,and a small number of other usefu l packages. One can then install additional conda packages from the conda repository.)

Miniconda + PySide6 works. It still works after I install numpy and pandas. But when I install matpotlib it stops working, with the same error message as before. So it seems that PySide6 is not compatible with matplotlib.

Thanks for the help @JonB. I'll ask about this in a matplotlib forum.

[SGaist]

Hi,

It's rather the other way around. Anaconda might not be providing a Matplotlib release with a backend for PySide6.

[Johan_R]

@SGaist I tried with PySide2 instead of Pyside6. I used a fresh Miniconda installation and I ran a PySide2 version of the Hello World program above.
Same behavior as before. It works with Miniconda + PySide2, keeps working after I install numpy and pandas, and stops working when I install matplotlib. The error message is almost the same as before

qt.qpa.plugin: Could not load the Qt platform plugin "windows" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: direct2d, minimal, offscreen, windows.

[SGaist]

Can you check where the plugins are loaded from before and after installing matplotlib ?

[Johan_R]

@SGaist

Before:
C:\Users\Rade\miniconda3\Lib\site-packages\PySide2\plugins\platforms\qwindows.dll

After:
C:\Users\Rade\miniconda3\Library\plugins\platforms\qwindows.dll

The folder C:\Users\Rade\miniconda3\Library\plugins does not exist before matplotlib is installed

[SGaist]

Then looks like it comes with its own build of Qt and they clash with the one of PySide2.

[Johan_R]

This post is deleted!

[Johan_R]

@SGaist You are absolutely right. matplotlib comes bundled with PySide6. If I install matplotlib and do not install my own PySide6, then the above Hello World program runs as expected. Problem solved.

Many thanks to @JonB and @SGaist for helping out with this!