diff -u b/core/modules/taxonomy/taxonomy.install b/core/modules/taxonomy/taxonomy.install
--- b/core/modules/taxonomy/taxonomy.install
+++ b/core/modules/taxonomy/taxonomy.install
@@ -11,13 +11,16 @@
  */
 
 /**
- * Update the parent field and make its definition computed.
+ * Change the parent field to computed for taxonomy_term.
  */
 function taxonomy_update_8300() {
   $entity_definition_update_manager = \Drupal::service('entity.definition_update_manager');
-  $field_definition = $entity_definition_update_manager->getFieldStorageDefinition('parent', 'taxonomy_term');
-  $field_definition->setComputed(TRUE);
-  $entity_definition_update_manager->updateFieldStorageDefinition($field_definition);
+  $storage_definition = $entity_definition_update_manager->getFieldStorageDefinition('parent', 'taxonomy_term');
+  // Computed field definitions are not tracked by the entity definition update
+  // manager, so remove the field storage definition for the parent field.
+  if ($storage_definition) {
+    $entity_definition_update_manager->uninstallFieldStorageDefinition($storage_definition);
+  }
 }
 
 /**