DLL load failed when importing PyQt5

Question

I have installed PyQt5 on windows platform and and getting an importError: DLL load failed.

I have installed pyqt5 using the command

pip3 install pyqt5
Successfully installed pyqt5-5.8.1

My Python version is as follows:

Python 3.5.2 |Anaconda custom (64-bit)| (default, Jul  5 2016, 11:41:13) [MSC v.1900 64 bit (AMD64)] on win32

The import Error is as follows:

from PyQt5.QtWidgets import QApplication
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: DLL load failed: The specified module could not be found.

Thanks & Regards

Answer 1

It is because of missing Python3.dll (stub dll, that re-exports Python3x.dll functions, so that one version of extension can work for multiple versions of python).

If your Python distro doesn't bundle python3.dll, you can try one from WinPython (https://winpython.github.io/).

At least the 2017/04/01 versions should have it.

1) Download WinPython ('Zero' version suffices; must be same "main version" - 3.5/3.6 -and "bitness" - 32/64 - as your Python !!!).

2) Extract to some temp directory, take the python3.dll and stick it into your python dir, next to the python3x.dll.

3) Enjoy working QT

Answer 2

I know the topic is old but I have also had this problem with the newest version of PyQT 5.11 but I've downgraded it to 5.9 via:

pip install PyQT5==5.9

and it has solved the issue.

Answer 3

If you created a virtualenv, check if python3.dll was copied into the Scripts directory of that virtualenv. Chances are only python35.dll (or python36.dll, etc., depending on the Python version) was copied, in which case you would get the error you're getting.