Update to Drupal 8.1.2. For more information, see https://www.drupal.org/project/drupal/releases/8.1.2

core/modules/path/path.module

@@ -38,7 +38,7 @@ function path_help($route_name, RouteMatchInterface $route_match) {
 }
 
 /**
- * Implements hook_form_BASE_FORM_ID_alter() for node_form().
+ * Implements hook_form_BASE_FORM_ID_alter() for \Drupal\node\NodeForm.
  */
 function path_form_node_form_alter(&$form, FormStateInterface $form_state) {
   $node = $form_state->getFormObject()->getEntity();

core/modules/path/src/Plugin/Field/FieldType/PathItem.php

@@ -90,4 +90,11 @@ class PathItem extends FieldItemBase {
     return $values;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function mainPropertyName() {
+    return 'alias';
+  }
+
 }

core/modules/path/src/Tests/PathAliasTest.php

@@ -59,7 +59,7 @@ class PathAliasTest extends PathTestBase {
     // @todo Remove this once https://www.drupal.org/node/2480077 lands.
     Cache::invalidateTags(['rendered']);
     $this->drupalGet(trim($edit['alias'], '/'));
-    $this->assertTrue(\Drupal::cache('data')->get('preload-paths:' .  $edit['source']), 'Cache entry was created.');
+    $this->assertTrue(\Drupal::cache('data')->get('preload-paths:' . $edit['source']), 'Cache entry was created.');
   }
 
   /**
@@ -345,4 +345,5 @@ class PathAliasTest extends PathTestBase {
     $this->assertText(t('The alias is already in use.'));
     $this->assertFieldByXPath("//input[@name='path[0][alias]' and contains(@class, 'error')]", $edit['path[0][alias]'], 'Textfield exists and has the error class.');
   }
+
 }

core/modules/path/src/Tests/PathLanguageTest.php

@@ -187,4 +187,5 @@ class PathLanguageTest extends PathTestBase {
     $english_node->save();
     $this->assertFalse($this->container->get('path.alias_storage')->aliasExists('/' . $french_alias, 'fr'), 'Alias for French translation is removed when translation is deleted.');
   }
+
 }

core/modules/path/src/Tests/PathLanguageUiTest.php

@@ -77,4 +77,5 @@ class PathLanguageUiTest extends PathTestBase {
     $this->drupalGet('fr/' . $name);
     $this->assertText(t('Filter aliases'), 'Foreign URL alias works');
   }
+
 }

core/modules/path/src/Tests/PathTaxonomyTermTest.php

@@ -82,4 +82,5 @@ class PathTaxonomyTermTest extends PathTestBase {
     $this->assertNoText($description, 'Old URL alias has been removed after altering.');
     $this->assertResponse(404, 'Old URL alias returns 404.');
   }
+
 }

core/modules/path/src/Tests/PathTestBase.php

@@ -25,4 +25,5 @@ abstract class PathTestBase extends WebTestBase {
       $this->drupalCreateContentType(array('type' => 'article', 'name' => 'Article'));
     }
   }
+
 }