Seeing this here as well on percona server 5.6.25-73.1-log, when started with super_read_only = ON it bails with "Event Scheduler: Failed to open table mysql.event". Disabling it fixed the issue.
Pretty nasty one, it actually submarined a full restart of 4 nodes I was doing to enable gtid, none of them came back up except the master!
Seeing this here as well on percona server 5.6.25-73.1-log, when started with super_read_only = ON it bails with "Event Scheduler: Failed to open table mysql.event". Disabling it fixed the issue.
Pretty nasty one, it actually submarined a full restart of 4 nodes I was doing to enable gtid, none of them came back up except the master!