Creates a site theme from an existing theme.

Adds column to a database table, if it doesn’t already exist.

If a table only contains utf8 or utf8mb4 columns, convert it to utf8mb4.

Creates a table in the database, if it doesn’t already exist.

Disables the Automattic widgets plugin, which was merged into core.

Disables the Link Manager on upgrade if, at the time of upgrade, no links exist in the DB.

Runs before the schema is upgraded.

Translate user level to user role name.

Executes network-level upgrade routines.

Checks the version of the installed MySQL binary.