automysqlbackup: Unknown table engine ‘PERFORMANCE_SCHEMA’

This error seems to be related to the MySQL-Bug #58406 (status: verified).

For the moment, you can ignore that message. The process skips the table and continues as always.
Whatever, if you want to make sure that your database has not been corrupted in consequence of this error, simply force mysqldump to ignore all performance_schema-tables.

Plesk way:

# mysqldump -uadmin -p`cat /etc/psa/.psa.shadow` --all-databases > /root/mysql.full.dump --ignore-table=performance_schema.cond_instances --ignore-table=performance_schema.events_waits_current --ignore-table=performance_schema.events_waits_history --ignore-table=performance_schema.events_waits_history_long  --ignore-table=performance_schema.events_waits_summary_by_instance --ignore-table=performance_schema.events_waits_summary_by_thread_by_event_name --ignore-table=performance_schema.events_waits_summary_global_by_event_name --ignore-table=performance_schema.file_instances --ignore-table=performance_schema.file_summary_by_event_name  --ignore-table=performance_schema.file_summary_by_instance  --ignore-table=performance_schema.mutex_instances --ignore-table=performance_schema.performance_timers  --ignore-table=performance_schema.rwlock_instances --ignore-table=performance_schema.setup_consumers --ignore-table=performance_schema.setup_instruments --ignore-table=performance_schema.setup_timers --ignore-table=performance_schema.threads

Default method:

# mysqldump -u root -p --all-databases > /root/mysql.full.dump --ignore-table=performance_schema.cond_instances --ignore-table=performance_schema.events_waits_current --ignore-table=performance_schema.events_waits_history --ignore-table=performance_schema.events_waits_history_long  --ignore-table=performance_schema.events_waits_summary_by_instance --ignore-table=performance_schema.events_waits_summary_by_thread_by_event_name --ignore-table=performance_schema.events_waits_summary_global_by_event_name --ignore-table=performance_schema.file_instances --ignore-table=performance_schema.file_summary_by_event_name  --ignore-table=performance_schema.file_summary_by_instance  --ignore-table=performance_schema.mutex_instances --ignore-table=performance_schema.performance_timers  --ignore-table=performance_schema.rwlock_instances --ignore-table=performance_schema.setup_consumers --ignore-table=performance_schema.setup_instruments --ignore-table=performance_schema.setup_timers --ignore-table=performance_schema.threads

and new dbdump function of automysqlbackup:

dbdump () {
	touch $2
	chmod 600 $2
	if [ $1 = "information_schema" ] ; then
		NEWOPT="--skip-opt ${OPT}"
        elif [ $1 = "performance_schema" ]; then
                NEWOPT="--skip-lock-tables --skip-opt ${OPT} \
                       --ignore-table=performance_schema.cond_instances \
                       --ignore-table=performance_schema.events_waits_current \
                       --ignore-table=performance_schema.events_waits_history \
                       --ignore-table=performance_schema.events_waits_history_long \
                       --ignore-table=performance_schema.events_waits_summary_by_instance \
                       --ignore-table=performance_schema.events_waits_summary_by_thread_by_event_name \
                       --ignore-table=performance_schema.events_waits_summary_global_by_event_name \
                       --ignore-table=performance_schema.file_instances \
                       --ignore-table=performance_schema.file_summary_by_event_name \
                       --ignore-table=performance_schema.file_summary_by_instance \
                       --ignore-table=performance_schema.mutex_instances \
                       --ignore-table=performance_schema.performance_timers \
...