Database mirroring is inactive for database 'xx'.

Starting up database 'XX'  (for all databases but the one in question)

The mirrored database "XX" is changing roles from "PRINCIPAL" to "MIRROR" because the mirroring session or availability group failed over due to role synchronization. This is an informational message only. No user action is required.

Following this was the recovery of all the other databases but this one.

The mirroring connection to "TCP://xxx.xxx.xxx:5022" has timed out for database "xxx" after 10 seconds without a response.  Check the service and network connections.

Database mirroring is inactive for database 'XX'. 

The mirrored database "XX" is changing roles from "MIRROR" to "PRINCIPAL" because the mirroring session or availability group failed over due to automatic failover

select mirroring_connection_timeout from sys.database_mirroring
where database_id = DB_ID('yourdb')