Scheduler fails with "ActiveRecord::ConnectionTimeoutError: could not obtain a connection from the pool within 5.000 seconds (waited 5.000 seconds); all pooled connections were in use>"

The supported way to fix this issue is setting environment variable POSTGRESQL_OPTIONS=?pool=50 in .env

This is a variable which was recently added to .env.

Check this out for more details : database.yml is in the wrong location for docker containers · Issue #5179 · zammad/zammad · GitHub