A minor maintenance issue. SOAPpy seems to be no longer maintained and does not support newest Python 3 releases. I've been using this fork instead SOAPpy-py3 which seems to be actively maintained. While I don't use all the features, the transition was painless and I didn't need to change any of my own code.

For reference, this is the documentation I'm talking about: https://docs.twisted.org/en/latest/installation/howto/optional.html