[MM3-users] Re: After server upgrade debian 11→12 and reinstalling everything in (venv), I got this error when accessing → mailman3/lists

I was directly replying to Marks answer, which does not work for me:

22:40 ...

This line is from a msg_footer imported from Mailman 2.1 by 'mailman import21'. The substitutions are not replaced because they are MM 2.1 syntax which MM 3 doesn't recognize.

If you have Mailman core >=3.3.10 and have set the Base Url parameter for the domain, you can replace that line in the template with simply

$mailinglist_url

If your Mailman core is older, you need to hardcode that as something like

https://example.com/mailman3/lists/$list_id

I'm only guessing here, but I suspect that you have some directories/files in the /opt/mailman/mm/var/templates/ hierarchy with mode and ownership such that they aren't readable by the Mailman user.