How to solve "Could not load the Qt platform plugin "cocoa" in "" even though it was found."

JimboNiss

I've got this same problem, when using py2app to compose a python Qt application. I can run the application from the py2app dist folder, just fine. However, after I copy it to /Applications, I get the same error...

Got keys from plugin meta data ("webgl")
QFactoryLoader::QFactoryLoader() checking directory path "/Applications/englauncher.app/Contents/MacOS/platforms" ...
Cannot load library /Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib: (dlopen(/Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib, 133): Library not loaded: @rpath/QtDBus.framework/Versions/5/QtDBus
Referenced from: /Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib
Reason: image not found)
QLibraryPrivate::loadPlugin failed on "/Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib" : "Cannot load library /Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib: (dlopen(/Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib, 133): Library not loaded: @rpath/QtDBus.framework/Versions/5/QtDBus\n Referenced from: /Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib\n Reason: image not found)"
qt.qpa.plugin: Could not load the Qt platform plugin "cocoa" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: cocoa, minimal, offscreen, webgl.

Anyone have any ideas?

SGaist

@JimboNiss hi and welcome to devnet,

What exactly do you have in your py2app folder ?
Do you have the QDbus framework in your app bundle ?

JimboNiss

@SGaist, not sure what you are asking, but I just updated py2app via pip3, as a test. Didn't help. Here is my setup.py for it:

"""
This is a setup.py script generated by py2applet

Usage:
python setup.py py2app
"""

from setuptools import setup

APP = ['englauncher.py']
DATA_FILES = [('', ['applescript'])]
#DATA_FILES = []
OPTIONS = {
'iconfile': 'icon_SEO.icns',
'packages': ['cffi']
}

setup(
app=APP,
data_files=DATA_FILES,
options={'py2app': OPTIONS},
setup_requires=['py2app'],
)

The QtDBus directory is in both /Applications/<app> and the py2app created ./disk/<app>...

Jims-MacBook-Pro:englauncher3 $ sudo find /Applications -name "QtDBus"
Password:
/Applications/englauncher.app/Contents/Resources/lib/python3.9/PyQt5/bindings/QtDBus
/Applications/englauncher.app/Contents/Resources/lib/python3.9/PyQt5/Qt5/lib/QtDBus.framework/Versions/5/QtDBus
Jims-MacBook-Pro:englauncher3 $ sudo find ./dist -name "QtDBus"
./dist/englauncher.app/Contents/Resources/lib/python3.9/PyQt5/Qt5/lib/QtDBus.framework/Versions/5/QtDBus
./dist/englauncher.app/Contents/Resources/lib/python3.9/PyQt5/bindings/QtDBus

SGaist

Can you check the rpath values of the executable ?

See here for more information about it.

JimboNiss

@SGaist said in How to solve "Could not load the Qt platform plugin "cocoa" in "" even though it was found.":

here

Ok, I was able to locate the rpath...

Jims-MacBook-Pro:englauncher3 $ otool -L ./dist/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib |grep -i qtdbus
@rpath/QtDBus.framework/Versions/5/QtDBus (compatibility version 5.15.0, current version 5.15.2)

Jims-MacBook-Pro:englauncher3 $ otool -L /Applications/englauncher.app/Contents/plugins/platforms/libqcocoa.dylib |grep -i qtdbus
@rpath/QtDBus.framework/Versions/5/QtDBus (compatibility version 5.15.0, current version 5.15.2)

https://stackoverflow.com/questions/12521802/print-rpath-of-an-executable-on-macos/12522096#125220
Jims-MacBook-Pro:englauncher3 $ otool -l dist/englauncher.app/Contents/MacOS/englauncher | grep RPATH -A2
cmd LC_RPATH
cmdsize 48
path @executable_path/../Frameworks (offset 12)
Jims-MacBook-Pro:englauncher3 $ otool -l dist/englauncher.app/Contents/MacOS/englauncher
Jims-MacBook-Pro:englauncher3 $ otool -l /Applications/englauncher.app/Contents/MacOS/englauncher | grep RPATH -A2
cmd LC_RPATH
cmdsize 48
path @executable_path/../Frameworks (offset 12)

Jims-MacBook-Pro:englauncher3 $ ls dist/englauncher.app/Contents/Frameworks
Python.framework libcrypto.1.1.dylib liblzma.5.dylib libmpdec.2.5.1.dylib libmpdec.3.dylib libssl.1.1.dylib
Jims-MacBook-Pro:englauncher3 $ ls /Applications/englauncher.app/Contents/Frameworks
Python.framework libcrypto.1.1.dylib liblzma.5.dylib libmpdec.2.5.1.dylib libmpdec.3.dylib libssl.1.1.dylib

What's odd is I can run the application from the dist directory just fine:
./dist/englauncher.app/Contents/MacOS/englauncher

But, I get the error when running it from /Applications:
/Applications/englauncher.app/Contents/MacOS/englauncher

I copied the application from ./dist to /Applications, so they should be the same.

hskoglund

HI, just guessing but maybe your app is picking up the QtDBus dylib from another place outside of your englauncher.app directory (and using relative paths).
To check, could you launch your app from the dist directory (i.e. where it runs successfully) and then open a Terminal and type
lsof -c englauncher
this will show what dlls/dylibs are loaded (and most importantly their paths).

JimboNiss

@hskoglund, the process doesn't keep running, so not sure I can run lsof on it.

Another thing I tried is completely uninstalling python3 from brew repository, and reinstalling it directly from python3, using Mac disk image. Had to reinstall my pip libraries, and got the same exact issue.

I'm at my wits end with this, and think it's a Big Sur issue, though can't prove it.

hskoglund

Hi, one way stop your app from exiting, you could try showing a message box, for example like this:

...
app = QApplication([])
alert = QMessageBox()
alert.setText('Click me when lsof -c is done')
alert.exec()
...

then you should have time to do a lsof -c englauncher

JimboNiss

@hskoglund, that didn't help, as it's not even able to load the Qt libraries. I even created a simple test app with your code, and while I can run it from ./dist/testapp, as soon as I copy it to /Applications, it fails loading the libraries in the same way.

hskoglund

Ok, please run that simple test app again from /dist/testapp, and while that QMessageBox is displayed, start a Terminal and type
lsof -c testapp

leotest

i have the same question,wait answer,please

leotest

no answer?please help

hskoglund

Hi, please create a new forum post and describe your problem, what version of Python and MacOS you have etc.

leotest

@hskoglund ok,thank u

mkcol

I fixed this on my machine by requiring py2app version 0.25

setup_requires=['py2app==0.25']
in the setup.py

This problem is described in https://github.com/ronaldoussoren/py2app/issues/380 and there's already a patch. Just don't use 0.26 and 0.27.