qt.qpa.plugin: 无法在“”中加载 Qt 平台插件 "xcb"，即使已找到。”

Question

我已经安装了 gqcnn, Pyrep and autolab_core。之后，我执行了同事写的代码，运行在他的电脑上运行正常。

但是，我无法运行代码。发生的错误是

python3.7/site-packages/cv2/qt/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/lib/python3.7/site-packages/cv2/qt/plugins/platforms/libqxcb.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/lib/python3.7/site-packages/cv2/qt/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archreq": 0,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 331520
}


In /home/bak/anaconda3/envs/pyrep/lib/python3.7/site-packages/cv2/qt/plugins/platforms/libqxcb.so:
  Plugin uses incompatible Qt library (5.15.0) [release]
"The plugin '/home/bak/anaconda3/envs/pyrep/lib/python3.7/site-packages/cv2/qt/plugins/platforms/libqxcb.so' uses incompatible Qt library. (5.15.0) [release]" 
         not a plugin
QFactoryLoader::QFactoryLoader() checking directory path "/home/bak/anaconda3/envs/pyrep/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqeglfs.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqeglfs.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "eglfs"
        ]
    },
    "className": "QEglFSIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqminimal.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqminimal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimal"
        ]
    },
    "className": "QMinimalIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqminimalegl.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqminimalegl.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "minimalegl"
        ]
    },
    "className": "QMinimalEglIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqoffscreen.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqoffscreen.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "offscreen"
        ]
    },
    "className": "QOffscreenIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqvnc.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqvnc.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "vnc"
        ]
    },
    "className": "QVncIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqxcb.so"
Found metadata in lib /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 329991
}


Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/bak/anaconda3/envs/pyrep/bin/platforms" ...
Cannot load library /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqxcb.so: (/home/bak/anaconda3/envs/pyrep/plugins/platforms/../../lib/libQt5XcbQpa.so.5: symbol _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform version Qt_5_PRIVATE_API not defined in file libQt5Gui.so.5 with link time reference)
QLibraryPrivate::loadPlugin failed on "/home/bak/anaconda3/envs/pyrep/plugins/platforms/libqxcb.so" : "Cannot load library /home/bak/anaconda3/envs/pyrep/plugins/platforms/libqxcb.so: (/home/bak/anaconda3/envs/pyrep/plugins/platforms/../../lib/libQt5XcbQpa.so.5: symbol _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform version Qt_5_PRIVATE_API not defined in file libQt5Gui.so.5 with link time reference)"
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/bak/anaconda3/envs/pyrep/lib/python3.7/site-packages/cv2/qt/plugins" 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: eglfs, minimal, minimalegl, offscreen, vnc, xcb.

如果您想详细查看完整错误，请参阅 here。上面的'/pyrep/'是我的anaconda环境名。

好像是qt引起的。但是我无法解决这个问题。

我应该怎么做才能解决这个问题？

Answer 1

这可能与similar error message有关。

我刚刚在 Ubuntu 20.04、Python 3.8 中遇到这个问题，同时尝试使用 matplotlib_backend_qtquick.

提到的线程中的这个答案为我解决了这个问题：https://askubuntu.com/a/1069502

Answer 2

终于找到解决办法了！ https://github.com/stepjam/PyRep/issues/76

问题是在 conda 环境中加载 Qt。

当我输入 qmake -version 时，终端 window 向我展示了 anaconda 中的 qt。按照上面的第一个答案URL，我可以解决问题。

Answer 3

当您将 opencv 与 pyqt5 一起使用时会出现此问题。看起来 opencv 内部使用的 qt 插件与 pyqt5 不兼容。只需在 import cv2 语句后取消设置环境变量 QT_QPA_PLATFORM_PLUGIN_PATH。

import os

os.environ.pop("QT_QPA_PLATFORM_PLUGIN_PATH")

您还可以在导入后更新平台插件路径opencv

import os

os.environ.update({"QT_QPA_PLATFORM_PLUGIN_PATH": "/home/udara/anaconda3/envs/research-headless/lib/python3.8/site-packages/PyQt5/Qt5/plugins/xcbglintegrations/libqxcb-glx-integration.so"})

请注意，这将使 opencv window 功能无法使用。如果你想使用它们，你必须在没有 qt 插件的情况下从源代码构建 opencv。您可以使用 gtk 插件而不是 qt.

构建 opencv

参考文献https://forum.qt.io/post/654289

Answer 4

我想在这里补充一点。

我遇到了这个问题，但在 debian10 上，none 提到的解决方案有所帮助。有帮助的是，在我的例子中，pip 默认安装了 pyqt5 的 5.15.2 版本。不过这里(https://repology.org/project/python:pyqt5/versions)说明debian10推荐的pyqt5版本是5.11.3.

当我用那个版本重新安装 pyqt5 时：

$ pip3 install PyQt5==5.11.3

问题已解决。关键是，检查一下可能是个好主意：

pip默认安装的是哪个版本的pyqt5
推荐一个人用哪个版本的pyqt5OS/distro

qt.qpa.plugin: 无法在“”中加载 Qt 平台插件 "xcb"，即使已找到。”

qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found."

python

opencv

qt5

anaconda