You have requested a non-existent parameter "app.root"

Problem/Motivation

After upgrading to Gutenberg 8.x-2.5 and running clear cache I get the following error:

Symfony\Component\DependencyInjection\Exception\RuntimeException: You have requested a non-existent parameter "app.root". in [error]
./vendor/symfony/dependency-injection/Compiler/DefinitionErrorExceptionPass.php:37
Stack trace:
#0 ./vendor/symfony/dependency-injection/Compiler/AbstractRecursivePass.php(60):
Symfony\Component\DependencyInjection\Compiler\DefinitionErrorExceptionPass->processValue(Object(Symfony\Component\DependencyInjection\Definition),
true)
#1 ./vendor/symfony/dependency-injection/Compiler/DefinitionErrorExceptionPass.php(30):
Symfony\Component\DependencyInjection\Compiler\AbstractRecursivePass->processValue(Array, true)
#2 ./vendor/symfony/dependency-injection/Compiler/AbstractRecursivePass.php(39):
Symfony\Component\DependencyInjection\Compiler\DefinitionErrorExceptionPass->processValue(Array, true)
#3 ./vendor/symfony/dependency-injection/Compiler/Compiler.php(140):
Symfony\Component\DependencyInjection\Compiler\AbstractRecursivePass->process(Object(Drupal\Core\DependencyInjection\ContainerBuilder))
#4 ./vendor/symfony/dependency-injection/ContainerBuilder.php(789):
Symfony\Component\DependencyInjection\Compiler\Compiler->compile(Object(Drupal\Core\DependencyInjection\ContainerBuilder))
#5 ./core/lib/Drupal/Core/DrupalKernel.php(1335):
Symfony\Component\DependencyInjection\ContainerBuilder->compile()
#6 ./core/lib/Drupal/Core/DrupalKernel.php(916): Drupal\Core\DrupalKernel->compileContainer()
#7 ./core/lib/Drupal/Core/DrupalKernel.php(477): Drupal\Core\DrupalKernel->initializeContainer()
#8 ./core/includes/utility.inc(38): Drupal\Core\DrupalKernel->boot()
#9 phar:///usr/local/bin/drush/commands/core/cache.drush.inc(302): drupal_rebuild(Object(Composer\Autoload\ClassLoader),
Object(Symfony\Component\HttpFoundation\Request))
#10 phar:///usr/local/bin/drush/includes/command.inc(422): drush_cache_rebuild()
#11 phar:///usr/local/bin/drush/includes/command.inc(231): _drush_invoke_hooks(Array, Array)
#12 phar:///usr/local/bin/drush/includes/command.inc(199): drush_command()
#13 phar:///usr/local/bin/drush/lib/Drush/Boot/BaseBoot.php(67): drush_dispatch(Array)
#14 phar:///usr/local/bin/drush/includes/preflight.inc(67): Drush\Boot\BaseBoot->bootstrap_and_dispatch()
#15 phar:///usr/local/bin/drush/includes/startup.inc(465): drush_main()
#16 phar:///usr/local/bin/drush/includes/startup.inc(369): drush_run_main(false, '/', 'Phar detected. ...')
#17 phar:///usr/local/bin/drush/drush(114): drush_startup(Array)
#18 /usr/local/bin/drush(10): require('phar:///usr/loc...')
#19 {main}

Steps to reproduce

1. Run on Drupal 8.9.20
2. Upgrade Gutenberg 8.x-2.5
3. run clear cache (i.e. drush cr)

Proposed resolution

I'm not really sure how to fix this. I tried changing '%app.root%' in gutenberg.services.yml back to '@app.root' but I was still getting the error. I also tried to load app.root via the ContainerInterface in BlocksLibraryManager.php (because at that point I couldn't really think where else there might be a problem) but I was still getting errors.

I was looking at this as reference for more information about the change of app.root from a service to a container: https://www.drupal.org/node/3080612

Not sure if this matters, but an additional detail is that my Drupal 8 project is a multi-site installation.

Remaining tasks

Pinpoint what's the cause of the bug

User interface changes

NA

API changes

NA

Data model changes

NA