The introduction of Drupal 9 will not make any major differences to the latest version of Drupal 8 in terms of the existing functionalities. With the release of Drupal 9, supported versions of software such as Twig 2 and Symfony 4/5 will be available. The biggest changes will be: removing the outdated code from the previous version, refining the media library, improving the admin UI and simplifying the Drupal validation. The minimum required PHP version will be 7.2 or even 7.3, which also increases performance. Some new features will not be finished with version 9.0, but will only be available with the following updates. The release of Drupal 9.1 and 9.2 are planned for the end of 2020 and mid-2021.
Drupal 8 and 9 come with a migration framework, which means that migrating content from previous versions, as well as from other systems, will be a simple task. This also applies to the code, the community has created its own page for "Converting Drupal 7 modules to Drupal 8“, which covers all common scenarios and problems.
Work continues on these functions and features:
- Admin interface
- Automatic updates
- JSON API
- Support for Symfony 4/5
- Support for Twig 2
- Bigpipe
- Cache tags
- Responsive images
- Improved inline editing
- Embedded media support
- Layout Builder
- Content Moderation
- Workspaces
- Configuration management
- Multilingual improvements
- API-First
- Support PHP 7.2+