When you start electrum or a software that uses PyQt5 with python3 you get a similar error:
electrum/gui/qt/__init__.py", line 35, in <module> from PyQt5.QtGui import * ModuleNotFoundError: No module named 'sip'
To solve this issue first uninstall PyQt5 and then install sip with python3 support
brew uninstall pyqt5 brew install pyqt5 --with-python3
If you still get the module not found error and you are using virtualenv, check this commands: Make sure the path to your venv is the correct one.
ln -s /usr/local/lib/python3.6/site-packages/sip.so /Users/youruser/.pyenv/versions/electrum/lib/python3.6/site-packages/sip.so ln -s /usr/local/lib/python3.6/site-packages/sip.pyi /Users/youruser/.pyenv/versions/electrum/lib/python3.6/site-packages/sip.pyi