Does there exist any library that can serve a WSGI application as a FastCGI server, for Python 3? (So that nginx could then proxy requests to it?)
The Python 3 docs ment
flipflop
pip3 install --upgrade flipflop
flipflop is what did the trick for me. flup-py3 has an unresolved issue which has been standing open for a couple of years now.
flup-py3
Do not forget to edit the import line in your .fcgi script to reflect this change towards using flipflop.
.fcgi