By Sam Moore on

When switching an existing D8 site from 5.5 to 5.6, it’s necessary to clear cache, because the compiled Twig files will all be incompatible (having been compiled under 5.5).
These files live in /sites/default/files/php/twig

If you switch an existing D8 site to 5.6, unless your site’s in dev mode, you’re going to get a 500 error on page load, and of course you won’t be able to get to your Performance page to clear cache from the admin interface; so use drush and do drush cache-rebuild
Worked for me, anyway.

⋅ Categories: Drupal 8.x