I inherited a site with Display Suite and Panels enabled. I have tried uninstalling both DS and Panels both before and after enabling Layout Builder.
If I try to enable Layout Builder without first uninstalling DS/Panels, I receive the following errors:
1: Location/Referrer = /admin/modules/list/confirm-experimental
Drupal\Core\Entity\Exception\NoCorrespondingEntityClassException: The Drupal\layout_builder\Entity\LayoutBuilderEntityViewDisplay class does not correspond to an entity type. in Drupal\Core\Entity\EntityTypeRepository->getEntityTypeFromClass() (line 98 of /core/lib/Drupal/Core/Entity/EntityTypeRepository.php).
2: Location: home page
Symfony\Component\Routing\Exception\RouteNotFoundException: Route "layout_builder.overrides.node.view" does not exist. in Drupal\Core\Routing\RouteProvider->getRouteByName() (line 201 of /core/lib/Drupal/Core/Routing/RouteProvider.php).
Regardless, when I navigate to Manage Display for any page type, I get a 404.
If I uninstall Layout Builder, the Manage Display route for any page type works again.
I have applied this patch, and it didn't make a difference: https://www.drupal.org/project/ds/issues/2966959#comment-12787545
