Why am I getting the error message "FATAL: remaining connection slots are reserved for non-replication superuser connections" in tower.log?

Issue

• Not able to access the UI for Automation Controller nor able to launch any jobs

• Seeing an error message similar to the following in /var/log/tower/tower.log

  File "/var/lib/awx/venv/awx/lib64/python3.9/site-packages/django/db/backends/postgresql/base.py", line 187, in get_new_connection
    connection = Database.connect(**conn_params)
  File "/var/lib/awx/venv/awx/lib64/python3.9/site-packages/psycopg2/__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
  django.db.utils.OperationalError: FATAL:  remaining connection slots are reserved for non-replication superuser connections