Error when editing Activity entity

OpenSocial Version: 8.x-1.0-rc5
Core Version: Drupal 8.3.2
URL: http://192.168.0.104/social/DIR/html/admin/structure/activity/1/edit

Not able to edit the Activity Entities. Drupal returns the error:The website encountered an unexpected error. Please try again later.

In the log, there are multiple errors.

Error Message 1:

Symfony\Component\Routing\Exception\InvalidParameterException: Parameter "selection_handler" for route "system.entity_autocomplete" must match "[^/]++" ("" given) to generate a corresponding URL. in Drupal\Core\Routing\UrlGenerator->doGenerate() (line 202 of /var/www/html/social/DIR/html/core/lib/Drupal/Core/Routing/UrlGenerator.php).

Error 2(This is logged 2 more times):

(Note: The company is a custom entity with just name and author fields. I am using template to have it create entry to activity feed.)

Notice: Undefined index: company_entity in Drupal\dynamic_entity_reference\Plugin\Field\FieldWidget\DynamicEntityReferenceWidget->createAutoCompletePaths() (line 239 of /var/www/html/social/DIR/html/modules/contrib/dynamic_entity_reference/src/Plugin/Field/FieldWidget/DynamicEntityReferenceWidget.php) #0 /var/www/html/social/DIR/html/core/includes/bootstrap.inc(552): _drupal_error_handler_real(8, 'Undefined index...', '/var/www/html/s...', 239, Array) #1 /var/www/html/social/DIR/html/modules/contrib/dynamic_entity_reference/src/Plugin/Field/FieldWidget/DynamicEntityReferenceWidget.php(239): _drupal_error_handler(8, 'Undefined index...', '/var/www/html/s...', 239, Array) #2 /var/www/html/social/DIR/html/modules/contrib/dynamic_entity_reference/src/Plugin/Field/FieldWidget/DynamicEntityReferenceWidget.php(118): Drupal\dynamic_entity_reference\Plugin\Field\FieldWidget\DynamicEntityReferenceWidget->createAutoCompletePaths(Array) #3 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Field/WidgetBase.php(322): Drupal\dynamic_entity_reference\Plugin\Field\FieldWidget\DynamicEntityReferenceWidget->formElement(Object(Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceFieldItemList), 0, Array, Array, Object(Drupal\Core\Form\FormState)) #4 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Field/WidgetBase.php(189): Drupal\Core\Field\WidgetBase->formSingleElement(Object(Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceFieldItemList), 0, Array, Array, Object(Drupal\Core\Form\FormState)) #5 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Field/WidgetBase.php(104): Drupal\Core\Field\WidgetBase->formMultipleElements(Object(Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceFieldItemList), Array, Object(Drupal\Core\Form\FormState)) #6 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php(168): Drupal\Core\Field\WidgetBase->form(Object(Drupal\dynamic_entity_reference\Plugin\Field\FieldType\DynamicEntityReferenceFieldItemList), Array, Object(Drupal\Core\Form\FormState)) #7 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Entity/ContentEntityForm.php(122): Drupal\Core\Entity\Entity\EntityFormDisplay->buildForm(Object(Drupal\activity_creator\Entity\Activity), Array, Object(Drupal\Core\Form\FormState)) #8 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Entity/EntityForm.php(115): Drupal\Core\Entity\ContentEntityForm->form(Array, Object(Drupal\Core\Form\FormState)) #9 /var/www/html/social/DIR/html/profiles/contrib/social/modules/custom/activity_creator/src/Form/ActivityForm.php(24): Drupal\Core\Entity\EntityForm->buildForm(Array, Object(Drupal\Core\Form\FormState)) #10 [internal function]: Drupal\activity_creator\Form\ActivityForm->buildForm(Array, Object(Drupal\Core\Form\FormState)) #11 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Form/FormBuilder.php(514): call_user_func_array(Array, Array) #12 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Form/FormBuilder.php(271): Drupal\Core\Form\FormBuilder->retrieveForm('activity_edit_f...', Object(Drupal\Core\Form\FormState)) #13 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Controller/FormController.php(74): Drupal\Core\Form\FormBuilder->buildForm('activity_edit_f...', Object(Drupal\Core\Form\FormState)) #14 [internal function]: Drupal\Core\Controller\FormController->getContentResult(Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\RouteMatch)) #15 /var/www/html/social/DIR/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(123): call_user_func_array(Array, Array) #16 /var/www/html/social/DIR/html/core/lib/Drupal/Core/Render/Renderer.php(574): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #17 /var/www/html/social/DIR/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(124): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure)) #18 /var/www/html/social/DIR/html/core/lib/Drupal/Core/EventSubscriber/EarlyRenderingControllerWrapperSubscriber.php(97): Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) #19 [internal function]: Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() #20 /var/www/html/social/DIR/vendor/symfony/http-kernel/HttpKernel.php(144): call_user_func_array(Object(Closure), Array) #21 /var/www/html/social/DIR/vendor/symfony/http-kernel/HttpKernel.php(64): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1) #22 /var/www/html/social/DIR/html/core/lib/Drupal/Core/StackMiddleware/Session.php(57): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #23 /var/www/html/social/DIR/html/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(47): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #24 /var/www/html/social/DIR/html/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(47): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #25 /var/www/html/social/DIR/html/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(50): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #26 /var/www/html/social/DIR/vendor/stack/builder/src/Stack/StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #27 /var/www/html/social/DIR/html/core/lib/Drupal/Core/DrupalKernel.php(656): Stack\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true) #28 /var/www/html/social/DIR/html/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request)) #29 {main}.