It’s no secret: upgrading Drupal 7 to 8 is riddled with new challenges unique to this particular version to version update. And while there is plenty of preparation to do in your steps to upgrade Drupal 7 to Drupal 8, most organizations will experience the bulk of their difficulties during the actual site to site migration. If you wish to continue using Drupal in the future, there is no possible way to avoid or bypass the Drupal 8 upgrade since Drupal 9 and every subsequent version of Drupal will use the new Symfony PHP framework in which Drupal 8 was rebuilt upon.
Luckily, Drupal 8 is more than three years old (as of this writing) and a whole community of Drupal developers and users have already documented most of the expected issues you could face throughout the upgrade process, including migration. Below is an overview of the migration process and some tips to reduce some of the common problems that occur.
The steps to upgrade Drupal 7 to Drupal 8 starts with understanding how your current Drupal site(s) is built through extensive preparation. Only after you are prepared, can you then begin migrating configurations, modules, and content.
Of course, you should first ensure your organization is prepared for the upcoming Drupal migration, which includes (but is not limited to) the following preparatory initiatives:
Drupal also recommends using the Drupal pre-upgrade analysis tool to estimate how much time and effort your team will ultimately need to complete the entire upgrade. In general, the upgrade implications will likely have the biggest impact on specific modules (which should be addressed during preparation), and your Drupal developers should be on-hand to offer insights into some of the more technical Drupal 8 module development your site might require during the migration.
Nonetheless, once you’ve adequately prepared, the migration activities can officially start. And depending on the complexity of your site structure, the amount of content, whether or not the migration is coupled with any re-design, and your general experience within the Drupal CMS, the migration can take many different forms.
With previous Drupal versioning updates, most developers simply migrated the structure directly and little hands-on involvement was needed to ensure everything continued functioning properly. The upgrade process updated the source site in-place. Site content and site configuration settings, for the most part, remained completely intact and most users barely noticed any changes.
Fast forward to Drupal 8, and things are much much different. As such, a multi-level migration approach is needed.
For brave and experienced Drupal users, it is possible to perform (carefully) most of the Drupal upgrade and migratory activities using the browser user interface, or you can also run the upgrade via Drush, though this will require a bit more technical expertise.
You’ll still want to perform all of the aforementioned prep work, but barring any big technical issues with module functionalities, it is certainly possible to complete most of the upgrade with minimal developer input. Before fully using the web browser, though, you’ll first migrate the modules.
To avoid issues will module migration, your migration project team should become familiar with all of the Drupal upgrade migration modules available for this process. Some are built into the core and ready to use after enabling them, others are contributed modules that you should only need to download if you anticipate any specific issues.
Luckily, the Drupal 8 web user interface does show a summary of which modules are automatically upgradable, and which ones are not.
Upgrading Drupal from the web browser involves the following steps:
Upgrading with Drush is more technical than the web browser version and you should consult with your Drupal developers or Drupal agency or simply have them run the upgrade entirely. The nice thing about Drush is that it allows you to do one-to-one migrations and rollbacks as needed. For additional information on all the steps and various ways to upgrade using Drush, you can reference Drupal’s helpful upgrade guide.
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