ModuleNotFoundError: No module named 'gi'

I installed Mopidy by means of PyPi on Debian stretch according to the instructions, so installed dependencies before. It runs on a compiled python3.7 with no other python version installed.
When I start mopidy I get this error:
ModuleNotFoundError: No module named 'gi'
Anyone has an idea?
Edit: apparently gi got installed in /usr/lib/python3/dist-packages. Putting this on PYTHONPATH made it find gi, but then got this error:
ImportError: cannot import name '_gi' from 'gi' (/usr/lib/python3/dist-packages/gi/

did you install mopidy in a virtual env (or conda env) ? If yes, I think that’s where the issue come from. There are issues with virtual envs and python-gi.
You could install mopidy with no virtualenv and that should work; I just found , maybe that could solve the problem as well, there is a section in the doc as well:

Thanks for the info. I’ll try to get Debian Buster up and running, because it has both python3.7 and gstreamer1.14 in the repo. Would be a better solution as I won’t need to recompile python3.7 again; took 4+ hours on an armhf architecture…

In the mean time have been able to get Debian Buster running. Installed mopidy through apt-get. Now if I want to install mopidy-mpd, it reports mopidy needs version 3 and it appears version 2.2.2 was installed.
I have looked around, checked the FAQ above, but how can I get version 3 on my system? Surprised it’s not on the repo.

Edit: deleted the apt-get repo version of mopidy, removed all and then installed the pypi version. It installs all the right dependencies and just seems to run fine :slight_smile: So the debian repo might need fixing, but the main stumble block seems a too old python3-pykka on the repo.