This application failed to start because no Qt platform plugin could be initialized.

[huskier]

After compiled the PythonQt, we try to run the example program PyGuiExample.exe in the lib directory, and we've gotten the following error. What's wrong with our program? Thanks in advance.

[mrbean-bremen]

This looks like your Qt installation is not found, or the wrong one is found. Have you checked that the plugins/platforms directory exists in the path of the Qt binaries, and that the Qt binaries are in the PATH?

[huskier]

@mrbean-bremen Thank you.
After added the user environment variable QT_QPA_PLATFORM_PLUGIN_PATH (value: C:\Application\Qt\5.15.2\msvc2019_64\plugins\platforms), the issue is fixed.

[huskier]

Sometimes the variable QT_QPA_PLATFORM_PLUGIN_PATH can make the QT application start significant slowly. I've encountered the slow problem on my PC, and finally I've located the problem is the variable QT_QPA_PLATFORM_PLUGIN_PATH. After delete the variable, my application could just fast as before.