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Troubleshooting

Since this is an early release and I'm the lone developer with access limited to MacOS, Ubuntu, and Windows 11. I'm looking for better solutions but I have a life outside of LatentEye so I'll do the best I can when I can. It's not you are paying for the software. :-)

Ubuntu notes

While this is mainly for Ubuntu it may so apply to other distro's as well but as of April 2025 I've only tested on Ubuntu 24.04 LTS.

PyQt / Qt seem to be really slow on Ubuntu and possibly other Linux Distros. I searched for a possible cause or solution using multiple methods. One of the comments I read about this issues said almost exactly "Thats Just The Way It Is" much as as I hate to say it unless someone knows a solution. That all I know. If anyone reading this knows a solution I'd love to hear it.

PROBLEM - Could not load xcb

qt.qpa.plugin: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is needed to load the Qt xcb platform plugin. qt.qpa.plugin: Could not load the Qt platform plugin "xcb" 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.

WHat the problem is

This error message means that your PyQt6 or Qt application is failing to start because the xcb platform plugin is either missing dependencies or not loading properly. Specifically:

  1. Missing xcb-cursor0 or libxcb-cursor0:

    • From Qt 6.5.0 onward, xcb-cursor0 (or libxcb-cursor0 depending on your system) is required for the xcb plugin.
    • Without it, the xcb plugin cannot initialize, causing Qt to fail.

  2. The xcb plugin was found but could not be loaded:

    • This suggests that xcb is installed but has missing dependencies or is incompatible.

  3. No Qt platform plugin could be initialized:

    • Qt needs a platform plugin (xcb, wayland, eglfs, etc.) to run on Linux. Since xcb isn't loading, it tries others but fails.

  4. Your available platform plugins are listed:

    • xcb is among them, but it won’t work until dependencies are fixed.

How to Fix

On Debian / Ubuntu

Try installing the missing xcb package and associted libraries:

sudo apt install libxcb-cursor0 libxcb-xinerama0 libxcb1 libx11-xcb1 libxcb-render-util0 libxcb-shape0 libxcb-xfixes0

On Fedora

sudo dnf install xcb-util-cursor

On Arch Linux

sudo pacman -S xcb-util-cursor

On OpenSUSE

sudo zypper install xcb-util-cursor

After installing the missing libraries, try running your application again.

If the issue persists, check whether QT_QPA_PLATFORM is set correctly:

echo $QT_QPA_PLATFORM

It should return xcb (or be empty). If it's something else, try forcing it:

export QT_QPA_PLATFORM=xcb
./your_qt_app

Postscript

There may be some issues with Qt and QTK one of the suggestions was: Set the following environment variable to enhance compatibility: QT_QPA_PLATFORM=xcb This adjustment ensures a smoother integration of QT applications with the chosen themes. After installation, you should observe improved theming consistency across your system.

As with most things YMMV. Try these step at your own risk. I am not responsible for any of your issues, problems, or data loss.

note: using the method mentioned above for Ubuntu 24.04 really improved the performance on my system. It now performs quite well. [Shrug] ahh... the wonders of multi-platform development.

Disclaimer

USE AT YOUR OWN RISK. What works for me, may not for you. I am not responsible for any data loss, OS failures, or any other data or computer system issues if you use the steps above.

Sources: