Why Are Drupal 7 Upgrades So Complex?

There's a lot of renewed buzz in the Drupal community surrounding Drupal 7 and upgrading to a modern version of Drupal given the Drupal Security Team's announcement regarding the extension of D7's EOL into January 2025. Invariably, when the topic of upgrade from D7 comes up so too comes the topic of the complexity of this upgrade. This article will dig into the top five reasons that make a Drupal 7 upgrade so hard:

Architectural Changes:

Drupal 8 introduced significant architectural changes, including the adoption of Symfony components and a shift to object-oriented programming. These changes required a rethinking of module development, theming, and overall site structure. Consequently, migrating from Drupal 7 to Drupal 10 or later versions often involves reworking or rewriting custom code and modules.

Deprecated Code and APIs:

Drupal 7 used certain code and APIs that have been deprecated and removed in later versions. This means that custom modules and themes built for Drupal 7 may not be compatible with newer Drupal versions. Upgrading these components requires identifying deprecated code, finding alternative solutions, and updating the codebase accordingly.

Data and Content Migration:

Migrating content and data from Drupal 7 to a newer version can be complex, especially if the site has a complex content structure or relies heavily on custom fields and configurations. Mapping the data structure and relationships between Drupal 7 and the target version is necessary to ensure a smooth transition. Content migration may involve using tools like the Migrate API and custom scripts to transfer data to the new Drupal version.

Contributed Module Compatibility:

Drupal's contributed module ecosystem is vast, and modules play a crucial role in extending the CMS's functionality. However, contributed modules may not always have immediate compatibility with newer Drupal versions. Upgrading from Drupal 7 often requires assessing and finding alternative modules or upgrading existing ones to their Drupal 10.

Theme and Design Changes:

Drupal 8 introduced a new theming system called Twig, which differs significantly from the PHP-based theming system used in Drupal 7. Migrating themes from Drupal 7 to newer versions involves rewriting or redesigning templates, updating CSS and JavaScript, and ensuring compatibility with the new theming system.

Where to go from here?

It is possible to maintain the same layout, design, regions, and even styles when migrating from a Drupal 7 if so desired. The only changes that must be made are to the template files and any underlying php logic (which must transition out of template files for performance and security reasons).

Check out What does it take to upgrade from Drupal 7 to Drupal 10? to dig deeper into the process of upgrading a site from D7 to a modern version of Drupal. The important thing now is to make sure that you have a plan for your upgrade and you put that plan into motion soon.