pyqt5报错：qt.qpa.plugin: Could not find the Qt platform plugin “xcb“（已解决）

我在使用pyqt库的时候报错：

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in \
"/mnt/private_disk/anaconda3/envs/aot-manip/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms" 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.

启动调试模式：export QT_DEBUG_PLUGINS=1，我发现这么一段报错：

QFactoryLoader::QFactoryLoader() checking directory path \
"/mnt/private_disk/anaconda3/envs/aot-manip/bin/platforms" ...
Cannot load library .../libqxcb.so: (/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5: undefined symbol: \
_ZN23QPlatformVulkanInstance22presentAboutToBeQueuedEP7QWindow, version Qt_5_PRIVATE_API)

这个undefined symbol的问题我之前也遇到过！

经过多番询问AI，发现了问题的缘由：

根据你的调试输出，核心问题在于 libQt5XcbQpa.so.5 中存在未定义的符号
_ZN23QPlatformVulkanInstance22presentAboutToBeQueuedEP7QWindow，这表明 ​Qt 库版本存在不兼容或依赖链断裂。

于是通过 ldd /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so 查看依赖的 Qt 库路径。我发现依赖的路径鱼龙混杂，有和anaconda相关的，有和coppeliaSim相关的，有在/usr/lib路径下的。

这和我之前使用CoppeliaSim时配置环境的遗留问题相关，执行vim ~/.bashrc，发现了之前的配置

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$COPPELIASIM_ROOT
export QT_QPA_PLATFORM_PLUGIN_PATH=$COPPELIASIM_ROOT
export LD_LIBRARY_PATH=/lib/x86_64-linux-gnu/:$LD_LIBRARY_PATH

解决方案比较简单，我首先注释掉了上面三行，不让pyqt去找系统目录下的LD_LIBRARY_PATH和QT_QPA_PLATFORM_PLUGIN_PATH。
然后在python代码中设置QT_QPA_PLATFORM_PLUGIN_PATH:

os.environ.update({"QT_QPA_PLATFORM_PLUGIN_PATH": \
"/mnt/private_disk/anaconda3/envs/aot-manip/lib/python3.8/site-packages/PyQt5/Qt5/plugins/platforms"})

网上还有一种配置方法export QT_QPA_PLATFORM_PLUGIN_PATH=/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms，据我猜测，这是使用c++开发Qt的配置方案，而我们用pip安装好的pyqt是自给自足的，不需要suda apt install Qt相关的库。