Dear Mark,
I upgraded the pypi packages as you suggested but the problem remains the same. Tried also installing from git heads but always get
==> /opt/hyperkitty_django/hyperkitty.log <== ERROR 2021-10-23 09:42:42,523 30765 hyperkitty.views.mailman The MAILMAN_ARCHIVER_KEY was not sent as the Authorization HTTP header. WARNING 2021-10-23 09:42:42,523 30765 django.request Unauthorized: /hyperkitty/api/mailman/urls WARNING 2021-10-23 09:42:42,523 30765 django.request Unauthorized: /hyperkitty/api/mailman/urls
==> /var/log/mailman/mailman.log <== Oct 23 07:42:42 2021 (30888) HyperKitty failure on http://127.0.0.1:8080/hyperkitty/api/mailman/urls: <html><title>Auth required</title><body> <h1>Authorization Required</h1><p>The archiver key must be sent over the Authorization HTTP header. </p></body></html> (401)
For information, how does your release cycle work? I prefer installing from a source rather than pypi. Is the master normally stable? When a packages lands on pypi? I'll stick on 1.3.4 / 1.1.0 for the moment.
All the best, Marco