Can confirm that mailman3 in oldstable/buster also appears affected by this regression, and the same mitigation (removing the trailing slash from the ProxyPass directive) works around it. (Found out while trying a fourth time to finish procrastinating on migrating my mailman2 system to mailman3 in prep for a procrastinated update to bullseye; the resulting stress was... not fun. :( )
Same symptoms in the mailman3-web log: WARNING 2021-10-17 17:01:08,583 12164 django.request Not Found: /mailman// WARNING 2021-10-17 17:01:08,583 12164 django.request Not Found: /mailman// Since uwsgi in oldstable, so far as I can tell, hasn't been so much as glanced at in two and a half years but Apache was security-updated within the last week or two, that has me wondering about where the bug really lies... uswgi versions: $ dpkg -l | grep uwsgi ii uwsgi 2.0.18-1 i386 fast, self-healing application container server ii uwsgi-core 2.0.18-1 i386 fast, self-healing application container server (core) ii uwsgi-plugin-python3 2.0.18-1 i386 WSGI plugin for uWSGI (Python 3) mailman3 versions: $ dpkg -l | grep mailman3 ii mailman3 3.2.1-1 all Mailing list management system ii mailman3-doc 3.2.1-1 all Mailing list management system documentation ii mailman3-full 3.2.1-1 all Full Mailman3 mailing list management suite (metapackage) ii mailman3-web 0+20180916-8 all Django project integrating Mailman3 Postorius and HyperKitty ii python3-django-mailman3 1.2.0-3 all Django library to help interaction with Mailman3 (Python 3 version) apache versions: $ dpkg -l | grep apache ii apache2 2.4.38-3+deb10u6 i386 Apache HTTP Server ii apache2-bin 2.4.38-3+deb10u6 i386 Apache HTTP Server (modules and other binary files) ii apache2-data 2.4.38-3+deb10u6 all Apache HTTP Server (common files) ii apache2-utils 2.4.38-3+deb10u6 i386 Apache HTTP Server (utility programs for web servers) Hope this helps. -jo -- Jo Valentine-Cooper (j...@nwcs.com) Of course, I don't know how interesting any of this really is, but now you've got it in your brain cells so you're stuck with it. --Gary Larson