After updating to Drupal 8.4 I now have an error in my browser when trying to load my Drupal site:

Error: Class '\Drupal\rest\PathProcessor\PathProcessorEntityResourceBC' not found in Drupal\Component\DependencyInjection\Container->createService() (line 262 of core/lib/Drupal/Component/DependencyInjection/Container.php)

If I execute a drush or drupal console command the error is the same but with more of a stacktrace.

I upgraded to Drush 9 which simplifies the error a bit more:

Service 'rest.path_processor_entity_resource_bc' for consumer 'path_processor_manager' does not implement Drupal\Core\PathProcessor\InboundPathProcessorInterface.

It looks like I have some dependency missing somewhere. I'm not sure how to track it down.

I have tried "composer install", "composer update", and removing the vendor directory and re-installing the composer packages but nothing has worked yet.

Has anyone had this error or know how to get the missing PathProcessorEntityResourceBC class?

  • How, exactly, did you update to 8.4? Commented Oct 9, 2017 at 14:23
  • I updated using drush (8.1 at the time) "drush up". Then I got some similar errors after the update. I managed to get passed the errors at the time by installing some drush dependency via composer and I got 8.4 working. I then committed & pushed my changes, and this morning I pulled my changes (of working 8.4) and updated the database with the latest version - and now I have the errors again (but not sure if they are the same missing classes that I had before). Basically I have my site on 2 machines, working on 1 and broken on the other. The code & database is exactly the same. Commented Oct 9, 2017 at 14:44
  • Is core installed via composer? If so, drush up will break things. In that case, I would revert to a backup and then update core through composer. Commented Oct 9, 2017 at 14:46
  • I can't remember exactly how it was installed, (probably just downloaded and unzipped core but possible that I installed it via composer - it's the only site I've had trouble with using 'drush up' on a few occasions) so that's good to know. Thanks, I will revert or post the answer if I find the problem. Commented Oct 9, 2017 at 14:55

1 Answer 1


I have fixed the error by replacing the 'core' directory with the latest 8.4.0 version. I then checked the git log and differences which were found in these files:

modified:   core/scripts/drupal.sh
modified:   core/scripts/password-hash.sh
modified:   core/scripts/rebuild_token_calculator.sh
modified:   core/scripts/run-tests.sh
modified:   core/scripts/update-countries.sh

The differences were similar for each file, for example:

--git a/core/scripts/update-countries.sh b/core/scripts/update-countries.sh

I'm not sure exactly how and why this fixed the missing class, but it seems like I have some differences between the 2 versions of the site.

I then added the changes into git on a new branch and after switching between the 2 branches I don't get the fatal error any more (with or without the updated files).

It's possible that something was cached and as my site and drush was broken I was unable to clear the cache, refreshing the core files must have fixed it.

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