The three config servers were migrated to CSRS and WiredTiger last week. Followed the documentation here : https://docs.mongodb.com/manual/tutorial/upgrade-config-servers-to-replica-set/ Since the change, when connected to a mongoS, we cannot see the databases after using show dbs and we cannot connect using –authenticationDatabase admin –username root –password xxxxx –authenticationMechanism SCRAM-SHA-1 There are no errors in any logs,Read more