joseverde@gmail.com writes:
Okay, so I got the webservice of Mailman3 up and running,
It would help to know how you did that. Did you wipe the server and start over? Did you just purge Mailman3 and its configuration files? Something else?
but when I go to mailman3/postorius/lists/, I get the following error:
Something went wrong Mailman REST API not available. Please start Mailman core.
When I logged in to the admin user, it threw a server 500 error, but I could refresh and see myself logged in.
The admin user is a Django concept. There isn't really one for Mailman core; it assumes you have direct access to the REST API. If you do have access to the REST API, you're the admin. So this doesn't prove anything about what core is doing or if it's running.
If I try to go to lists or mailman settings, however, I get the error above.
The webservice is two front ends, Postorius for administration and HyperKitty for list traffic archives. You mention only Postorius. Is HyperKitty running?
The problem here could be several different things. Mailman core, Postorius, and HyperKitty are separate processes, communicating over TCP sockets. If Postorius says core isn't running, that just means it was unable to open a socket to connect to core. Core might be running but listening on a different port than the one Postorius expects, or it might not be running, and there are probably arcane reasons it could fail even if it's running and they have the same port configured.
You can can check whether Mailman core is running in several ways, depending on what Ubuntu 18.04 uses to control daemons. If it's systemd, then "systemctl status mailman" (or maybe "... mailman3") should do the trick.
If core is not running, you need to start it, and figure out how to get that to happen automatically since it didn't happen this time.
If core is running, most likely either the webservice(s) or the core are misconfigured as to the port where core is providing the REST API. But we'll cross that bridge when we get to it, as there are a number of configuration files involved.