PyQt6: DLL load failed while importing QtGui: The specified procedure could not be found.

tanzi

My Environment

OS: Windows 10
Python: 3.9.9
Anaconda: Anaconda3-2022.05-Windows-x86_64
vitual environment: base,PyQt6

The output of the command pip list when the virtual environment is "PyQt6":

Package          Version
---------------- ---------
click            7.1.2
pip              21.3.1
PyQt6            6.1.0
pyqt6-plugins    6.1.0.2.2
PyQt6-Qt6        6.3.1
PyQt6-sip        13.4.0
pyqt6-tools      6.1.0.3.2
python-dotenv    0.20.0
qt6-applications 6.1.0.2.2
qt6-tools        6.1.0.1.2
setuptools       60.5.0
wheel            0.37.1

The output of the command pip list|findstr "Qt" when the virtual environment is "base"

PyQt6                         6.3.1
PyQt6-Qt6                     6.3.1
PyQt6-sip                     13.4.0
QtAwesome                     1.0.3
QtPy                          2.0.1

The issue

When the vritual environment is "PyQt6", the code from PyQt6 import QtWidgets throws the error below

DLL load failed while importing QtGui: The specified procedure could not be found.

But, when the vritual environment is "base", the code runs normally

Why?How to solve it?

tanzi

Another test

First step, create a brand-new virtual environment, and then install PyQt6

conda create -n PyQt6_2 python=3.9.9
conda activate PyQt6_2
pip install PyQt6

Then, test the code from PyQt6 import QtWidgets

Python
>> from PyQt6 import QtWidgets

Everything runs fine now.

Second step, install PyQt6-tools

pip install PyQt6-tools

Then, the code from PyQt6 import QtWidgets will throw the error PyQt6: DLL load failed while importing QtGui: The specified procedure could not be found.

Comparsion

Before I installed PyQt6 , the output of pip list was

Package    Version
---------- -------
pip        21.3.1
PyQt6      6.3.1
PyQt6-Qt6  6.3.1
PyQt6-sip  13.4.0
setuptools 60.5.0
wheel      0.37.1

After I installed PyQt6 , the output of pip list was

Package          Version
---------------- ---------
click            7.1.2
pip              21.3.1
PyQt6            6.1.0
pyqt6-plugins    6.1.0.2.2
PyQt6-Qt6        6.3.1
PyQt6-sip        13.4.0
pyqt6-tools      6.1.0.3.2
python-dotenv    0.20.0
qt6-applications 6.1.0.2.2
qt6-tools        6.1.0.1.2
setuptools       60.5.0
wheel            0.37.1

The tests on base and PyQt6 virtual environments are the same with this test.

In the first test, the virtual environment base installed PyQt6 and not installed PyQt6-tools

JonB

@tanzi
Sounds potentially like a "DLL found but required symbol within DLL not found", an inconsistency within the C++ Qt DLLs or between them and PyQt6. I would search my whole disk for e.g. dir /s/b Qt*.DLL. Any mixed versions? Any Qt5 artefacts? What version of PyQt6 versus Qt6 do you see?

Plinio B

the problem starts on PyQt version 6.0.3. Do not install other modules that depends on the version above 6.03. I solve the issue by installing PyQt 6.0.2 and pyqt6-tools 6.0.2

my version list is the following

Package Version

click 7.1.2
pip 21.3.1
PyQt6 6.0.2
pyqt6-plugins 6.0.2.2.2
PyQt6-Qt 6.0.1
PyQt6-Qt6 6.0.2
PyQt6-sip 13.4.0
pyqt6-tools 6.0.2.3.2
python-dotenv 0.20.0
qt6-applications 6.0.2.2.2
qt6-tools 6.0.2.1.2
setuptools 60.2.0
wheel 0.37.1