PHP exception when saving a registration type and entity_redirect module is enabled

Hi thanks for your post. Can you provide more details? What is the name of the registration type and what other modules are installed. Adding a registration type is working for other D10 sites and is passing tests.

the error happens whatever the registration type name. After checking with a clean install, the incompatibility is with the module entity_redirect, which otherwise works as expected

here's the trace, I hope this helps

TypeError: Cannot access offset of type string on string in Drupal\Component\Utility\NestedArray::setValue() (line 155 of core/lib/Drupal/Component/Utility/NestedArray.php).

Drupal\Core\Form\FormBuilder->handleInputElement() (Line: 1003)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 1073)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 1073)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 1073)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 1073)
Drupal\Core\Form\FormBuilder->doBuildForm() (Line: 577)
Drupal\Core\Form\FormBuilder->processForm() (Line: 323)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 580)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 163)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 58)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 686)
Drupal\Core\DrupalKernel->handle() (Line: 19)

The problem is in the entity_redirect module. It injects itself into other module's forms using a generically named form element named "workflow" that is commonly used in other modules that use the Workflows module in Drupal core. Any bundle entity type that already has a "workflow" element will then fail with a PHP exception. This is also happening with the commerce_order module as noted here:
https://www.drupal.org/project/entity_redirect/issues/3267587 🐛 Cannot save commerce order type with entity_redirect enabled Active
And it will happen with other modules in the future. That module's maintainer needs to use a more unique name such as "entity_redirect_workflow" for that element.

Please open an issue in that module's issue queue.