ImportError: dlopen(/usr/local/lib/python3.6/site-packages/PyQt5/QtGui.so, 2): Symbol not found: __cg_png_create_info_struct

[Manfred Sever]

Hi everyone,

any time I try and import pyqtgraph in a python script (either version 2.7 or 3.6) I now get the error:

.......

    import pyqtgraph as pg

  File "/usr/local/lib/python3.6/site-packages/pyqtgraph/__init__.py", line 13, in <module>

    from .Qt import QtGui

  File "/usr/local/lib/python3.6/site-packages/pyqtgraph/Qt.py", line 153, in <module>

    from PyQt5 import QtGui, QtCore, QtWidgets, uic

ImportError: dlopen(/usr/local/lib/python3.6/site-packages/PyQt5/QtGui.so, 2): Symbol not found: __cg_png_create_info_struct

  Referenced from: /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO

  Expected in: /opt/local/lib/libPng.dylib

 in /System/Library/Frameworks/ImageIO.framework/Versions/A/ImageIO

I had installed PyQt5 a while ago and was working fine until I also had to install XQuartz, latest MacOS Xcode, Mac Ports, gcc5, wget, cmake, gmake, automake, autoconf, libtool, m4, pkgconfig, mango.

Does anyone know how to fix this?

I _need_ to be able to plot to continue my research.

Thanks,

Manfred.