Migrate a Drupal 8 Site to Drupal 9 on Pantheon

Discuss in our Forum Discuss in Slack

This guide provides common troubleshooting tasks when migrating to Drupal 9 with Integrated Composer.

Pantheon Launch Check Status Error: services.yml does not exist

After you set up Drupal 9, you might see this error in the Best practices section of the Pantheon Launch Check:

x sites/default/services.yml: services.yml does not exist! Copy the default.service.yml to services.yml and see for details.

Create services.yml file inside sites/default directory by copying default/services.yml file. See for details.

Ensure your site's Development Mode is set to Git, then use the terminal on the local machine where you cloned the site, and from the project's root directory:

  1. Copy to services.yml:

    cp web/sites/default/ web/sites/default/services.yml
  2. Commit and push:

    git add web/sites/default/services.yml && git commit -m "init services.yml"
    git push origin master

Learn more about the service configuration file.

Error: Class ViewPageController Does Not Exist

As reported in Drupal Issue 3161309, some fresh installations may encounter the error:

InvalidArgumentException: Class "Drupal\views\Routing\ViewPageController" does not exist.

If you encounter this error, clear the cache through the Site Dashboard, or with the Terminus drush cr command:

terminus drush <site>.<env> -- cr

Given the nature of the bug, it might be easier to reinstall Drupal 9.

Pantheon Drupal 8 Modules Being Upgraded to Drupal 9

Module NameDrupal 8 Version?Drupal 9 Version?
Pantheon Advanced Page CacheYesYes
Search API PantheonYesNot yet

Where can I report an issue?

Contact support to report any issues that you encounter.