diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteWidgetBase.php b/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteWidgetBase.php
index 50caf2f..d69a99a 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteWidgetBase.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/Plugin/field/widget/AutocompleteWidgetBase.php
@@ -77,10 +77,15 @@ public function formElement(FieldInterface $items, $delta, array $element, array
 
     // Prepare the autocomplete path.
     $autocomplete_path = $this->getSetting('autocomplete_path');
-    $autocomplete_path .= '/' . $this->fieldDefinition->getFieldName() . '/' . $entity->entityType() . '/' . $entity->bundle();
-    // Use <NULL> as a placeholder in the URL when we don't have a real entity
-    // (most web servers collapse two consecutive slashes.)
-    $autocomplete_path .= '/' . ($entity->id() ?: 'NULL');
+    $autocomplete_path .= '/' . $this->fieldDefinition->getFieldName() . '/' . $entity->entityType() . '/' . $entity->bundle() . '/';
+
+    // Use <NULL> as a placeholder in the URL when we don't have an entity.
+    // Most web servers collapse two consecutive slashes.
+    $id = 'NULL';
+    if ($entity && $entity_id = $entity->id()) {
+      $id = $entity_id;
+    }
+    $autocomplete_path .= $id;
 
     $element += array(
       '#type' => 'textfield',