MySQL 8 was released in 2018, but many MySQL servers are still running MySQL 5.x. Oracle has ended support for MySQL 5.7 and plans to phase out its support by October 2023. Upgrading from MySQL 5.7 to MySQL 8 is recommended due to performance improvements and security enhancements. Before upgrading, it's essential to ensure a backup of the database, as the upgrade process may require downtime or changes to character sets, collations, obsolete data types, authentication mechanisms, reserved words, SQL modes, and other settings. Upgrading with no downtime can be achieved using tools like PlanetScale's import tool, which allows importing a live production database without data loss or downtime. It's crucial to test the database thoroughly after the upgrade to ensure it functions correctly.