Too few arguments in ConditionalFieldsElementAlterHelper.php

Could not reproduce this error.
ConditionalFieldsElementAlterHelper does require 2 arguments, see ConditionalFieldsElementAlterHelper.php line 38
These 2 arguments are defined and provided in conditional_fields.services.yml line 24
So if only 0 are being passed it implies that the updated conditional_fields.services.yml file is not being respected. Clearing cache (drush cache-rebuild) should resolve the issue.

No need of any changes required because The ConditionalFieldsElementAlterHelper is already correctly defined in services.yml with the necessary arguments (like @module_handler and @entity_type.manager). i have reviewed the code.

@lieb I also had this. drush cr didn't help me, but this did:

$ drush php

then:

\Drupal::service('cache.discovery')->invalidateAll();

@gedvan - Thanks! That worked for me!