Does EM need to be restarted when APM DB was restarted?
It is recommended to restart Enterprise Manager (MOM, Collector EM and Standalone) when APM DB was restarted.
If the database connection of EM gets stale and gets active later, EM is unable to reconnect / recover.
In this case EM gets the exceptions for Misfirehandler, because Scheduler Jobs(QuartzJob) unable to get fresh databse connections.
[ERROR] [QuartzScheduler_ExportReports-one_MisfireHandler] [org.quartz.impl.jdbcjobstore.JobStoreTX] MisfireHandler: Error handling misfires: Failed to obtain DB connection from data source 'cemdb': java.sql.SQLException: Can't allocate JDBC connection