Fix ImportError: unable to find Qt5Core.dll on PATH Error: A Completed Guide – PyQT Tutorial

By | November 22, 2019

We will use pyqt to develop our python ui application, however, we find this error: ImportError: unable to find Qt5Core.dll on PATH. In this tutorial, we will introduce you how to fix this problem.

Fix unable to find Qt5Core.dll on PATH Error

Open PyQT5\

You will see source code like this:

dll_dir = os.path.dirname(__file__) + '\\Qt\\bin'
    if os.path.isfile(dll_dir + '\\Qt5Core_conda.dll'):
        path = dll_dir + ';' + path
        os.environ['PATH'] = path

Print out dll_dir, in our environment, it is:


Because we install pyqt using anaconda, we will notice where is file ‘Qt5Core_conda.dll‘.

Anaconda Install PyQT: A Completed Guide

From code above, this file should be in C:\Users\fly165\.conda\envs\py3.7\lib\site-packages\PyQt5\Qt\bin, however, it is not?

Where is Qt5Core_conda.dll?

We will search this file with everything (a file search engine).

qt5core_conda.dll installation path

From above, we find this file is installed into: C:\Users\fly165\.conda\pkgs\qt-5.12.5-h7ef1ec2_0\Library\bin

Check the version we have installed qt

conda install pyqt 5.12.5

Comparing with them, we find qt-5.12.5 is not installed into our python environment by anaconda, it is installed into C:\Users\fly165\.conda\pkgs.

How to fix this error?

Change dll_dir to:

#dll_dir = os.path.dirname(__file__) + '\\Qt\\bin'
dll_dir = r'C:\Users\fly165\.conda\pkgs\qt-5.12.5-h7ef1ec2_0\Library\bin'

Run pyqt srouce code, we will find this error is fixed. Here is our pyqt window example.

pyqt simple window example