Page not found after installing extension in Drupal 8 and Drupal 9
After you install a new extension (for example data processor) in a Drupal 8 or Drupal 9 environment the pages of this extension could not be found.
A work around is to clear the Drupal caches afterwards.
Related PR: https://github.com/civicrm/civicrm-core/pull/19888