MySQL 5.7 Release Notes
        
- Downgrade is only supported between General Availability (GA) releases. 
- Downgrade from MySQL 5.7 to 5.6 is supported using the logical downgrade method. 
- Downgrade that skips versions is not supported. For example, downgrading directly from MySQL 5.7 to 5.5 is not supported. 
- Downgrade within a release series is supported. For example, downgrading from MySQL 5.7. - zto 5.7.- yis supported. Skipping a release is also supported. For example, downgrading from MySQL 5.7.- zto 5.7.- xis supported.