3.1 Before You Begin

Understand what may occur during an upgrade. See Section 3.4, “What the MySQL Upgrade Process Upgrades”.

Protect your data by creating a backup. The backup should include the mysql system database, which contains the MySQL data dictionary tables and system tables. See Section 9.2, “Database Backup Methods”.

Important

Downgrade from MySQL 9.0 to MySQL 8.4, or from a MySQL 9.0 release to a previous MySQL 9.0 release, is not supported. The only supported alternative is to restore a backup taken before upgrading. It is therefore imperative that you back up your data before starting the upgrade process.

Review Section 3.2, “Upgrade Paths” to ensure that your intended upgrade path is supported.

Review Section 3.5, “Changes in MySQL 9.0” for changes that you should be aware of before upgrading. Some changes may require action.

Review Section 1.4, “What Is New in MySQL 9.0” for deprecated and removed features. An upgrade may require changes with respect to those features if you use any of them.

Review Section 1.5, “Server and Status Variables and Options Added, Deprecated, or Removed in MySQL 9.0 since 8.4”. If you use deprecated or removed variables, an upgrade may require configuration changes.

Review the Release Notes for information about fixes, changes, and new features.

If you use replication, review Section 19.5.3, “Upgrading or Downgrading a Replication Topology”.

Review Section 3.3, “Upgrade Best Practices” and plan accordingly.

Upgrade procedures vary by platform and how the initial installation was performed. Use the procedure that applies to your current MySQL installation:

For binary and package-based installations on non-Windows platforms, refer to Section 3.7, “Upgrading MySQL Binary or Package-based Installations on Unix/Linux”.
Note
For supported Linux distributions, the preferred method for upgrading package-based installations is to use the MySQL software repositories (MySQL Yum Repository, MySQL APT Repository, and MySQL SLES Repository).
For installations on an Enterprise Linux platform or Fedora using the MySQL Yum Repository, refer to Section 3.8, “Upgrading MySQL with the MySQL Yum Repository”.
For installations on Ubuntu using the MySQL APT repository, refer to Section 3.9, “Upgrading MySQL with the MySQL APT Repository”.
For installations on SLES using the MySQL SLES repository, refer to Section 3.10, “Upgrading MySQL with the MySQL SLES Repository”.
For installations performed using Docker, refer to Section 3.12, “Upgrading a Docker Installation of MySQL”.
For installations on Windows, refer to Section 3.11, “Upgrading MySQL on Windows”.

If your MySQL installation contains a large amount of data that might take a long time to convert after an in-place upgrade, it may be useful to create a test instance for assessing the conversions that are required and the work involved to perform them. To create a test instance, make a copy of your MySQL instance that contains the mysql database and other databases without the data. Run the upgrade procedure on the test instance to assess the work involved to perform the actual data conversion.

Rebuilding and reinstalling MySQL language interfaces is recommended when you install or upgrade to a new release of MySQL. This applies to MySQL interfaces such as PHP mysql extensions and the Perl DBD::mysql module.