Migrating from a previous version of Drupal
Drupal ships with a couple of core modules that assist you in updating your site from Drupal 6 or 7 to Drupal 10. The architecture between previous versions of Drupal before version 8 was radically different in design, and you cannot upgrade from 6 or 7 the same way you can from 8 or 9.
To mitigate the challenges of upgrading from Drupal 6 or 7, the Migrate Drupal module helps prepare a new environment for your older Drupal database to migrate to and is included in the core release of Drupal 10.
Custom modules, custom themes, and custom Drush commands
An important thing to note about upgrading from versions of Drupal prior to version 8 is that you will need to manually port custom modules, custom theme(s), and custom Drush commands you may have created. There are no tools to automate this, and they will not work until you have ported them to be compatible with Drupal 10. This must be done prior to upgrading, or you may encounter...