It can happen that Exchange 2019 servers log the EventID 1006 (source: MSExchange Mailbox Replication). The text of the warning is as follows:
Source: MSExchange Mailbox Replication
EventID: 1006
The Microsoft Exchange Mailbox Replication service was unable to process jobs in a mailbox database.
Database: Missing database (393e425f-0b1b-4ee2-98d5-c4737febdc5d)
Error: Database '393e425f-0b1b-4ee2-98d5-c4737febdc5d' doesn't exist.
The warning occurs approximately every 2 minutes. The warning occurs when a database has been deleted and is fortunately very easy to resolve. It is not a problem with the Exchange databases. The "Microsoft Exchange Mailbox Replication" service just needs to be restarted:
The service can be restarted during operation, the restart has no influence on the clients or availability. After restarting the service, the messages should no longer appear.