This is known issue for MYSQL DBs and we need to convert all the tables to use InnoDB engine.
You can use the below SQL to generate the commands to alter the tables to InnoDB engine.
SELECT concat('ALTER TABLE ',TABLE_NAME,' ENGINE=InnoDB;')
WHERE TABLE_SCHEMA = 'ambaridb' AND ENGINE = 'MyISAM' AND TABLE_TYPE='BASE TABLE';
Once we get the output , remove the ' | ' and run the alter commands.
Once we run alter commands, commit and exit mysql.
and than run ambari-server upgrade.