How to fix “ImportError: unable to find Qt5Core.dll on PATH” after pyinstaller bundled the python application

Question

Can\'t run QT based GUI application bundled by pyinstaller, the console output shows it is due to an import error:

ImportError: unable to find

Answer 1

I solved this for myself by commenting all in site-packages\PyQt5\__init__.py and adding this code from an older version of QT __init__.py:

import os as _os

_path = _os.path.dirname(__file__) + '\\Qt\\bin;' + _os.environ['PATH']
_os.environ['PATH'] = _path

Answer 2

As detailed in the question, when startup the bundled application in the conda console, it runs properly, all the loaded DLLs, exported by ProcessExplorer, are in the dist dir which was created by pyinstaller. So the problem is that the path, containing pyqt DLLs, is not in the system's PATH environment. Maybe this is a bug of pyinstaller. The Solution is add the program path to system PATH env manually.

Here is the code snip i am using:

# Fix qt import error
# Include this file before import PyQt5 

import os
import sys
import logging


def _append_run_path():
    if getattr(sys, 'frozen', False):
        pathlist = []

        # If the application is run as a bundle, the pyInstaller bootloader
        # extends the sys module by a flag frozen=True and sets the app
        # path into variable _MEIPASS'.
        pathlist.append(sys._MEIPASS)

        # the application exe path
        _main_app_path = os.path.dirname(sys.executable)
        pathlist.append(_main_app_path)

        # append to system path enviroment
        os.environ["PATH"] += os.pathsep + os.pathsep.join(pathlist)

    logging.error("current PATH: %s", os.environ['PATH'])


_append_run_path()

Answer 3

Assuming you don't absolutely need PyQt5 version 5.13.0, the easiest fix is to simply downgrade PyQt5 to version 5.12.2 using:

pip install pyqt5==5.12.2

and your executable will work as expected.

Answer 4

I comment all content of file site-packages\PyQt5\__init__.py and install again. It works.

I use python3.5 with PyInstaller=3.5 and PyQt5=5.13.0.The packaged exe is working on my computer, but does not work on others. The error message is:

 File "anaconda3\lib\site-packages\PyInstaller\loader\pyimod03_importers.py", line 627, in exec_module
  File "site-packages\PyQt5\__init__.py", line 41, in <module>
  File "site-packages\PyQt5\__init__.py", line 33, in find_qt
ImportError: unable to find Qt5Core.dll on PATH

So I see site-packages\PyQt5\__init__.py(5.13.0) is:

def find_qt():
    import os

    path = os.environ['PATH']

    dll_dir = os.path.dirname(__file__) + '\\Qt\\bin'
    if os.path.isfile(dll_dir + '\\Qt5Core.dll'):
        path = dll_dir + ';' + path
        os.environ['PATH'] = path
    else:
        for dll_dir in path.split(';'):
            if os.path.isfile(dll_dir + '\\Qt5Core.dll'):
                break
        else:
            raise ImportError("unable to find Qt5Core.dll on PATH")

    try:
        os.add_dll_directory(dll_dir)
    except AttributeError:
        pass


find_qt()
del find_qt

I think PyQt5 can't find the PATH in the other computer although Qt5Core.dll already exists in the project directly. So I commented out the file and now it works.

Answer 5

Ran into the same issue after upgrade to Qt5.13.
Found this solution on pyinstaller github
You need to modify the .spec file and put the following:

datas=[(HOMEPATH + '\\PyQt5\\Qt\\bin\*', 'PyQt5\\Qt\\bin')],