ImportError：dlopen（/Users/Desktop/myapp/target/myapp_mac/cv2/cv2.cpython-36m-darwin.so，2）

Question

I'm using Pyinstaller and OpenCV in MacOS. After building my standalone application, I'm getting the error below. I've tried different versions of the modules, but nothing worked for me.

I'm Using

• MacOs version: 10.14.5
• python : 3.6
• pyinstaller : 3.4
• opencv-python : 3.4.5

The error:

File "main.py", line 19, in <module>
  File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/PyInstaller/loader/pyimod03_importers.py", line 627, in exec_module
    exec(bytecode, module.__dict__)
  File "site-packages/cv2/__init__.py", line 3, in <module>
ImportError: dlopen(/Users/Desktop/myapp/target/myapp_mac/cv2/cv2.cpython-36m-darwin.so, 2): Symbol not found: __ZN10QBoxLayout10invalidateEv
  Referenced from: /Users/Desktop/myapp/target/myapp_mac/cv2/cv2.cpython-36m-darwin.so
  Expected in: /Users/Desktop/myapp/target/myapp_mac/PyQt5/../QtGui
 in /Users/Desktop/myapp/target/myapp_mac/cv2/cv2.cpython-36m-darwin.so

Answer 1

In short, depending on your project, try the package opencv-python-headless instead of opencv-python

I just got this working for my self. the problem appears to be the package opencv-python is linked to Qt4, py installer copies the Qt5 binaries from PySide2 and thus the symbol can't be found.

from opencv-python-headless :

$ otool -L venv/lib/python3.7/site-packages/cv2/cv2.cpython-37m-darwin.so
venv/lib/python3.7/site-packages/cv2/cv2.cpython-37m-darwin.so:
        /System/Library/Frameworks/OpenCL.framework/Versions/A/OpenCL (compatibility version 1.0.0, current version 1.0.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1238.50.2)
        @loader_path/.dylibs/libavcodec.58.35.100.dylib (compatibility version 58.0.0, current version 58.35.100)
        @loader_path/.dylibs/libavformat.58.20.100.dylib (compatibility version 58.0.0, current version 58.20.100)
        @loader_path/.dylibs/libavutil.56.22.100.dylib (compatibility version 56.0.0, current version 56.22.100)
        @loader_path/.dylibs/libswscale.5.3.100.dylib (compatibility version 5.0.0, current version 5.3.100)
        @loader_path/.dylibs/libavresample.4.0.0.dylib (compatibility version 4.0.0, current version 4.0.0)
        /System/Library/Frameworks/Accelerate.framework/Versions/A/Accelerate (compatibility version 1.0.0, current version 4.0.0)
        /System/Library/Frameworks/AVFoundation.framework/Versions/A/AVFoundation (compatibility version 1.0.0, current version 2.0.0)
        /System/Library/Frameworks/ApplicationServices.framework/Versions/A/ApplicationServices (compatibility version 1.0.0, current version 1070.22.0)
        /System/Library/Frameworks/CoreMedia.framework/Versions/A/CoreMedia (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/CoreVideo.framework/Versions/A/CoreVideo (compatibility version 1.2.0, current version 1.5.0)
        /System/Library/Frameworks/QuartzCore.framework/Versions/A/QuartzCore (compatibility version 1.2.0, current version 1.11.0)
        /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 22.0.0)
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 307.5.0)
        /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit (compatibility version 45.0.0, current version 1504.82.104)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1349.64.0)
        /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation (compatibility version 300.0.0, current version 1349.63.0)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)

from opencv-python :

$ otool -L venv/lib/python3.7/site-packages/cv2/cv2.cpython-37m-darwin.so
venv/lib/python3.7/site-packages/cv2/cv2.cpython-37m-darwin.so:
        /System/Library/Frameworks/OpenCL.framework/Versions/A/OpenCL (compatibility version 1.0.0, current version 1.0.0)
        /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1238.50.2)
        @loader_path/.dylibs/libavcodec.58.35.100.dylib (compatibility version 58.0.0, current version 58.35.100)
        @loader_path/.dylibs/libavformat.58.20.100.dylib (compatibility version 58.0.0, current version 58.20.100)
        @loader_path/.dylibs/libavutil.56.22.100.dylib (compatibility version 56.0.0, current version 56.22.100)
        @loader_path/.dylibs/libswscale.5.3.100.dylib (compatibility version 5.0.0, current version 5.3.100)
        @loader_path/.dylibs/libavresample.4.0.0.dylib (compatibility version 4.0.0, current version 4.0.0)
        /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 22.0.0)
        /System/Library/Frameworks/Accelerate.framework/Versions/A/Accelerate (compatibility version 1.0.0, current version 4.0.0)
        /System/Library/Frameworks/AVFoundation.framework/Versions/A/AVFoundation (compatibility version 1.0.0, current version 2.0.0)
        /System/Library/Frameworks/ApplicationServices.framework/Versions/A/ApplicationServices (compatibility version 1.0.0, current version 1070.22.0)
        /System/Library/Frameworks/CoreMedia.framework/Versions/A/CoreMedia (compatibility version 1.0.0, current version 1.0.0)
        /System/Library/Frameworks/CoreVideo.framework/Versions/A/CoreVideo (compatibility version 1.2.0, current version 1.5.0)
        /System/Library/Frameworks/QuartzCore.framework/Versions/A/QuartzCore (compatibility version 1.2.0, current version 1.11.0)
        @loader_path/.dylibs/QtGui (compatibility version 4.8.0, current version 4.8.7)
        @loader_path/.dylibs/QtTest (compatibility version 4.8.0, current version 4.8.7)
        @loader_path/.dylibs/QtCore (compatibility version 4.8.0, current version 4.8.7)
        /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 307.5.0)
        /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1349.64.0)
        /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation (compatibility version 300.0.0, current version 1349.63.0)
        /usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)

I did read that the headless can be used if your code is not calling cv2.imshow(...) . I am going to investigate further because the the windows version doesn't ship with the qt binaries and doesn't have the same problem