diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 5b821c8de0..12b9324402 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -338,7 +338,11 @@ public function wasDefaultRevision() {
     if (!$this->getEntityType()->isRevisionable()) {
       throw new \LogicException("Entity type {$this->getEntityTypeId()} does not support revisions.");
     }
-    return (bool) $this->get('default_revision')->value;
+    $value = $this->get('default_revision')->value;
+    if (isset($value)) {
+      return (bool) $value;
+    }
+    throw new \LogicException("Missing data for the \"default_revision\" field on the entity {$this->getEntityTypeId()}:{$this->id()}.");
   }
 
   /**
@@ -1303,8 +1307,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
         ->setLabel(new TranslatableMarkup('Default revision'))
         ->setDescription(new TranslatableMarkup('A flag indicating whether this was a default revision when it was saved.'))
         ->setTranslatable(FALSE)
-        ->setRevisionable(TRUE)
-        ->setRequired(TRUE);
+        ->setRevisionable(TRUE);
     }
 
     if ($entity_type->hasKey('langcode')) {
diff --git a/core/lib/Drupal/Core/Entity/EntityFieldManager.php b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
index 040a34c681..63c35e9743 100644
--- a/core/lib/Drupal/Core/Entity/EntityFieldManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
@@ -220,8 +220,7 @@ protected function buildBaseFieldDefinitions($entity_type_id) {
       }
     }
 
-    // Make sure that revisionable and translatable entity types are correctly
-    // defined.
+    // Make sure that revisionable entity types are correctly defined.
     if ($entity_type->isRevisionable() && $entity_type->isTranslatable()) {
       // The 'revision_translation_affected' field should always be defined.
       // This field has been added unconditionally in Drupal 8.4.0 and it is
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
index fb497523bd..3b15161380 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
@@ -384,18 +384,19 @@ protected function updateFieldStorageDefinitionsToRevisionable(ContentEntityType
     }
     $updated_storage_definitions[$entity_type->getKey('revision')] = $revision_field;
 
-    $revision_type_field = BaseFieldDefinition::create('boolean')
-      ->setName('default_revision')
+    // Add the default revision flag.
+    $field_name = 'default_revision';
+    $default_revision_field = BaseFieldDefinition::create('boolean')
+      ->setName($field_name)
       ->setLabel(new TranslatableMarkup('Default revision'))
       ->setDescription(new TranslatableMarkup('A flag indicating whether this was a default revision when it was saved.'))
       ->setTranslatable(FALSE)
-      ->setRevisionable(TRUE)
-      ->setRequired(TRUE);
+      ->setRevisionable(TRUE);
 
     if ($update_cached_definitions) {
-      $this->entityDefinitionUpdateManager->installFieldStorageDefinition($revision_type_field->getName(), $entity_type->id(), $entity_type->getProvider(), $revision_type_field);
+      $this->entityDefinitionUpdateManager->installFieldStorageDefinition($default_revision_field->getName(), $entity_type->id(), $entity_type->getProvider(), $default_revision_field);
     }
-    $updated_storage_definitions[$revision_type_field->getName()] = $revision_type_field;
+    $updated_storage_definitions[$default_revision_field->getName()] = $default_revision_field;
 
     // Add the 'revision_translation_affected' field if needed.
     if ($entity_type->isTranslatable()) {
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 2f59ad4255..38c63517f7 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -2061,32 +2061,34 @@ function system_update_8403() {
  * Add the 'revision_type' field to all entity types.
  */
 function system_update_8501() {
+  /** @var \Drupal\Core\Entity\EntityFieldManagerInterface $field_manager */
+  $field_manager = \Drupal::service('entity_field.manager');
   $definition_update_manager = \Drupal::entityDefinitionUpdateManager();
 
-  // Get a list of revisionable entity types.
+  // Get a list of entity types to process.
   /** @var \Drupal\Core\Entity\ContentEntityTypeInterface[] $definitions */
-  $definitions = array_filter(\Drupal::entityTypeManager()->getDefinitions(), function (EntityTypeInterface $entity_type) use ($definition_update_manager) {
-    if ($entity_type = $definition_update_manager->getEntityType($entity_type->id())) {
-      return $entity_type->isRevisionable();
+  $definitions = array_filter(\Drupal::entityTypeManager()->getDefinitions(), function (EntityTypeInterface $entity_type) use ($field_manager, $definition_update_manager) {
+    $entity_type_id = $entity_type->id();
+    if ($entity_type = $definition_update_manager->getEntityType($entity_type_id)) {
+      $field_name = 'default_revision';
+      return $entity_type->isRevisionable()
+        && isset($field_manager->getFieldStorageDefinitions($entity_type_id)[$field_name])
+        && !$definition_update_manager->getFieldStorageDefinition($field_name, $entity_type_id);
     }
     return FALSE;
   });
 
+  $storage_definition = BaseFieldDefinition::create('boolean')
+    ->setLabel(t('Default revision'))
+    ->setDescription(t('A flag indicating whether this was a default revision when it was saved.'))
+    ->setTranslatable(FALSE)
+    ->setRevisionable(TRUE)
+    ->setInitialValue(TRUE);
+
+  // Install the 'default_revision' field.
   foreach ($definitions as $entity_type_id => $entity_type) {
     $field_name = 'default_revision';
-
-    // Install the 'default_revision' field if needed.
-    if (!$definition_update_manager->getFieldStorageDefinition($field_name, $entity_type_id)) {
-      $storage_definition = BaseFieldDefinition::create('boolean')
-        ->setLabel(t('Default revision'))
-        ->setDescription(t('A flag indicating whether this was a default revision when it was saved.'))
-        ->setTranslatable(FALSE)
-        ->setRevisionable(TRUE)
-        ->setRequired(TRUE)
-        ->setInitialValue(TRUE);
-
-      $definition_update_manager
-        ->installFieldStorageDefinition($field_name, $entity_type_id, $entity_type_id, $storage_definition);
-    }
+    $definition_update_manager
+      ->installFieldStorageDefinition($field_name, $entity_type_id, $entity_type_id, $storage_definition);
   }
 }
diff --git a/core/modules/system/tests/modules/entity_test_update/src/Entity/EntityTestUpdate.php b/core/modules/system/tests/modules/entity_test_update/src/Entity/EntityTestUpdate.php
index 286e8e62bd..175bc7ad80 100644
--- a/core/modules/system/tests/modules/entity_test_update/src/Entity/EntityTestUpdate.php
+++ b/core/modules/system/tests/modules/entity_test_update/src/Entity/EntityTestUpdate.php
@@ -69,11 +69,17 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDescription(new TranslatableMarkup('The bundle of the test entity.'))
       ->setRequired(TRUE);
 
-    if ($entity_type->hasKey('revision')) {
+    if ($entity_type->isRevisionable()) {
       $fields[$entity_type->getKey('revision')] = BaseFieldDefinition::create('integer')
         ->setLabel(new TranslatableMarkup('Revision ID'))
         ->setReadOnly(TRUE)
         ->setSetting('unsigned', TRUE);
+
+      $fields['default_revision'] = BaseFieldDefinition::create('boolean')
+        ->setLabel(new TranslatableMarkup('Default revision'))
+        ->setDescription(new TranslatableMarkup('A flag indicating whether this was a default revision when it was saved.'))
+        ->setTranslatable(FALSE)
+        ->setRevisionable(TRUE);
     }
 
     $fields[$entity_type->getKey('langcode')] = BaseFieldDefinition::create('language')