Upgrading to core 8.8 results in a path alias error
Pathauto 8.x-1.6  is the only version working with both Drupal 8.7 and 8.8. So first update Pathauto to this version, then update core and then update Pathauto to the current version. Run drush updb in each step. See the change record http://drupal.org/node/3089457.