Yes. And why isn't that added to the documentation yet, I am just asking.
It does not yet fix the other next issue (SystemError: initialization of _psycopg raised unreported exception) where I did not say anything about postgresql.... (settings and mailmain info looks fine; grep is silent about pg in any settings file, all pg-stuff is commented-out, look)
/etc/mailman3/grep pg * mailman-web.py: # Use 'sqlite3', 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'. mailman-web.py: #'ENGINE': 'django.db.backends.postgresql_psycopg2', mailman-web.py:# management command after each code upgrade. mailman-web.py.backup: # Use 'sqlite3', 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'. mailman-web.py.backup: #'ENGINE': 'django.db.backends.postgresql_psycopg2', mailman-web.py.backup:# management command after each code upgrade. mailman-web.py.ucf-dist: # Use 'sqlite3', 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'. mailman-web.py.ucf-dist: #'ENGINE': 'django.db.backends.postgresql_psycopg2', mailman-web.py.ucf-dist:# management command after each code upgrade. grep: __pycache__: Is a directory settings.py:# 'ENGINE': 'django.db.backends.postgresql_psycopg2', settings.py: # Use 'sqlite3', 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'. settings.py: #'ENGINE': 'django.db.backends.postgresql_psycopg2',