Updating mysql version
To perform a major version upgrade for a My SQL version 5.5 DB instance on Amazon RDS to My SQL version 5.6 or later, you should first perform any available OS updates.After OS updates are complete, you must upgrade to each major version: 5.5 to 5.6, and then 5.6 to 5.7.
The second DB snapshot is taken when the upgrade completes.For information on Amazon RDS DB instance classes, see DB Instance Class.Major version upgrades can contain database changes that are not backward-compatible with existing applications.My SQL major version upgrades typically complete in about 10 minutes. Even though upgrades take place during the instance maintenance window, we still schedule them at specific times through the year.Some upgrades might take longer because of the DB instance class size or because the instance doesn't follow certain operational guidelines in Best Practices for Amazon RDS. We schedule them so you can plan around them, because downtime is required to upgrade a DB engine version, even for Multi-AZ instances.When you are ready, you can perform version upgrades at the times that best fit your schedule.
If your DB instance is using read replication, you must upgrade all of the Read Replicas before upgrading the source instance.
If your DB instance is in a Multi-AZ deployment, both the primary and standby DB instances are upgraded.
The primary and standby DB instances are upgraded at the same time and you will experience an outage until the upgrade is complete.
The only issue after the upgrade may be TIMESTAMP entries.
Now, even after an do-release-upgrade to 16.04, mysql is still left at 5.6 and the issues surrounding the non-supported upgrade from 5.5 directly to 5.7 during the release upgrade never even surface.
Once the option says mysql-5.7, scroll down on the main menu to Apply and press ENTER again. 5.7), which is not a supported upgrade path as documented by mysql.