Update to Drupal 8.2.4. For more information, see https://www.drupal.org/project/drupal/releases/8.2.4

core/modules/user/migration_templates/d6_user.yml

@@ -5,6 +5,8 @@ migration_tags:
 source:
   plugin: d6_user
 process:
+  # If you are using this file to build a custom migration consider removing
+  # the uid field to allow incremental migrations.
   uid: uid
   name: name
   pass: pass

core/modules/user/migration_templates/d6_user_picture_file.yml

@@ -11,6 +11,9 @@ source:
     # table are specified, and must end with a /.
     source_base_path: ''
 process:
+    # If you are using both this migration and d6_file in a custom migration
+    # and executing migrations incrementally, it is recommended that you
+    # remove the fid mapping from d6_file to avoid potential ID conflicts.
   filename: filename
   uid: uid
   source_full_path:

core/modules/user/migration_templates/d7_user.yml

@@ -6,6 +6,8 @@ class: Drupal\user\Plugin\migrate\User
 source:
   plugin: d7_user
 process:
+  # If you are using this file to build a custom migration consider removing
+  # the uid field to allow incremental migrations.
   uid: uid
   name: name
   pass: pass

core/modules/user/migration_templates/user_picture_field.yml

@@ -18,4 +18,7 @@ process:
   type: 'constants/type'
   cardinality: 'constants/cardinality'
 destination:
-  plugin: md_entity:field_storage_config
+  plugin: entity:field_storage_config
+  dependencies:
+    module:
+      - image

core/modules/user/migration_templates/user_profile_field.yml

@@ -32,4 +32,4 @@ process:
     map:
       list: -1
 destination:
-  plugin: md_entity:field_storage_config
+  plugin: entity:field_storage_config

core/modules/user/tests/src/Functional/UserLoginHttpTest.php

@@ -10,6 +10,7 @@ use GuzzleHttp\Cookie\CookieJar;
 use Psr\Http\Message\ResponseInterface;
 use Symfony\Component\Serializer\Encoder\JsonEncoder;
 use Symfony\Component\Serializer\Encoder\XmlEncoder;
+use Drupal\hal\Encoder\JsonEncoder as HALJsonEncoder;
 use Symfony\Component\Serializer\Serializer;
 
 /**
@@ -19,6 +20,13 @@ use Symfony\Component\Serializer\Serializer;
  */
 class UserLoginHttpTest extends BrowserTestBase {
 
+  /**
+   * Modules to install.
+   *
+   * @var array
+   */
+  public static $modules = ['hal'];
+
   /**
    * The cookie jar.
    *
@@ -39,7 +47,7 @@ class UserLoginHttpTest extends BrowserTestBase {
   protected function setUp() {
     parent::setUp();
     $this->cookies = new CookieJar();
-    $encoders = [new JsonEncoder(), new XmlEncoder()];
+    $encoders = [new JsonEncoder(), new XmlEncoder(), new HALJsonEncoder()];
     $this->serializer = new Serializer([], $encoders);
   }
 
@@ -90,7 +98,7 @@ class UserLoginHttpTest extends BrowserTestBase {
         /** @var \Drupal\Core\Extension\ModuleInstaller $module_installer */
         $module_installer = $this->container->get('module_installer');
         $module_installer->install(['serialization']);
-        $formats = ['json', 'xml'];
+        $formats = ['json', 'xml', 'hal_json'];
       }
       else {
         // Without the serialization module only JSON is supported.