[MM3-users] "Something went wrong" HTTP Error 500: {"title": "500 Internal Server Error"}

zachr@mta.ca writes:

Ive had a look at historical posts and I think this might be related to this issue: https://lists.mailman3.org/archives/list/mailman-users@mailman3.org/thread/I...

Pretty sure that is NOT the issue. This is quite different:

configparser.InterpolationSyntaxError: '%' must be followed by '%' or '(', found: '%#$%sfdgs'

Somewhere in your Mailman configurations, probably in /etc/mailman3/mailman.cfg, you will find the string '%# $%sfdgs' (possibly with different or no quotes), likely in a line something like

API_KEY = '%#$%sfdgs'

or

API_KEY: '%#$%sfdgs'

Change that to '%%#$%%sfdgs' (ie, double both of the '%' characters) and restart mailman (or mailmanweb if you found it in settings.py).