# Symbol Not Found in PyQt6 on macOS Mojave when Running PsychoPy

**URL:** <https://discourse.psychopy.org/t/symbol-not-found-in-pyqt6-on-macos-mojave-when-running-psychopy/41456>\
**Category:** Online experiments\
**Created:** [September 18, 2024, 6:31pm UTC](https://discourse.psychopy.org/t/symbol-not-found-in-pyqt6-on-macos-mojave-when-running-psychopy/41456 "2024-09-18T18:31:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ilkekav](https://avatars.discourse-cdn.com/v4/letter/i/b782af/32.png) [@ilkekav](https://discourse.psychopy.org/u/ilkekav)\
**Post date:** [September 18, 2024, 6:31pm UTC](https://discourse.psychopy.org/t/symbol-not-found-in-pyqt6-on-macos-mojave-when-running-psychopy/41456/1 "2024-09-18T18:31:48Z")

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Hello,

I’m encountering an issue when trying to run an experiment on PsychoPy version 2024.2.1 on my Mac running macOS Mojave 10.14.6. Below is the error message I receive:ImportError: dlopen(/Applications/PsychoPy.app/Contents/Resources/lib/python3.8/PyQt6/QtCore.abi3.so, 2): Symbol not found: \_objc\_opt\_class  
Referenced from: /Applications/PsychoPy.app/Contents/Resources/lib/python3.8/PyQt6/Qt6/lib/QtCore.framework/Versions/A/QtCore (which was built for Mac OS X 11.0)  
Expected in: /usr/lib/libobjc.A.dylib  
in /Applications/PsychoPy.app/Contents/Resources/lib/python3.8/PyQt6/Qt6/lib/QtCore.framework/Versions/A/QtCore  
################# Experiment ended with exit code 1 [pid:4329] #################-  
I would appreciate any guidance or suggestions on how to resolve this issue. Has anyone else encountered something similar?

Thanks in advance!

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**Author:** ![jonathan.kominsky](https://avatars.discourse-cdn.com/v4/letter/j/a587f6/32.png) [@jonathan.kominsky](https://discourse.psychopy.org/u/jonathan.kominsky)\
**Post date:** [September 19, 2024, 7:10am UTC](https://discourse.psychopy.org/t/symbol-not-found-in-pyqt6-on-macos-mojave-when-running-psychopy/41456/2 "2024-09-19T07:10:06Z")

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PyQt6 does not play nice with versions of MacOS older than 11.0 (Big Sur), as far as I can tell, or at least the version of it that comes with PsychoPy seems to be built for Big Sur or newer versions of MacOS. I think the 2023 versions of PsychoPy used PyQt5, or at least 2023.1 did, so if you downgrade to an older version of PsychoPy it might work better, as long as that doesn’t break anything else.