I have been trying to get a mailman 3 installation working for longer than I'd like to admit. Core appears to be installed and working as desired but Postorius (and hyperkitty, but I haven't even started troubleshooting it while trying to get the web interface working) is only loading the main page with no lists shown and all remaining links return a server error (specific text is: "Server error An error occurred while processing your request." with the error text highlighted). I think I followed all of the installation instructions, including the updated pythonpath line in the systemd module, but it's entirely possible that there is an error somewhere along the way.
I have had to make two minor tweaks, the /static/ location was moved from /opt/mailman/web/static to /var/www/mailman/ (owner mailman:nginx) as nginx was giving permissions errors (even if it owned the files or with the mod set to 777) with the default location and wouldn't load the css, and installed postgres directly from their repo as the method in the guide doesn't create the user. Aside from that everything should be exactly as laid out in the installation guide.
The logs are showing everything running and the DB logs show all the queries going through successfully, there are no errors in the web logs corresponding with the errors being served on the site aside an entry for a 500 in the access logs
[18/May/2021:12:13:01] "GET /archives/ HTTP/1.1" 500 1102 "http://mailman3/mailman3/lists/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.91 Safari/537.36" "-"
when I took a look in the DB tables many of them appear to be empty, I have a few lists in core that were imported from 2.1 but no new lists created.
Mailman: 3.3.4 Postorius: 1.3.4 OS: Oracle Linux 8.3 Python: 3.6 postgres: 13.2