diff --git a/core/modules/block/block.install b/core/modules/block/block.install
index 01c5779..1b9396b 100644
--- a/core/modules/block/block.install
+++ b/core/modules/block/block.install
@@ -246,23 +246,23 @@ function block_update_8008() {
 
     // First, create the body field.
     $body_field = array(
-      'field_name' => 'block_body',
+      'id' => 'block_body',
       'type' => 'text_with_summary',
       'entity_types' => array('custom_block'),
       'module' => 'text',
       'cardinality' => 1,
     );
-    _update_7000_field_create_field($body_field);
+    _update_8000_field_create_field($body_field);
 
     $instance = array(
-      'field_name' => 'block_body',
+      'id' => 'custom_block.basic.block_body',
       'entity_type' => 'custom_block',
       'bundle' => 'basic',
       'label' => 'Block body',
       'widget' => array('type' => 'text_textarea_with_summary'),
       'settings' => array('display_summary' => FALSE),
     );
-    _update_7000_field_create_instance($body_field, $instance);
+    _update_8000_field_create_instance($body_field, $instance);
 
     // Initialize state for future calls.
     $sandbox['last'] = 0;
@@ -302,7 +302,7 @@ function block_update_8008() {
         );
         // This is a core update and no contrib modules are enabled yet, so
         // we can assume default field storage for a faster update.
-        _update_7000_field_sql_storage_write('custom_block', 'basic', $block->bid, $block->bid, 'block_body', $data);
+        _update_8000_field_sql_storage_write('custom_block', 'basic', $block->bid, $block->bid, 'block_body', $data);
 
         $sandbox['last'] = $block->bid;
         $sandbox['count'] += 1;
diff --git a/core/modules/field/field.install b/core/modules/field/field.install
index 2ea53a9..a90d311 100644
--- a/core/modules/field/field.install
+++ b/core/modules/field/field.install
@@ -11,14 +11,16 @@
 /**
  * Creates a field by writing directly to configuration.
  *
+ * @param array $field_config
+ *   An array of field properties.
+ *
  * @ingroup update_api
  */
-function _update_7000_field_create_field(&$field) {
+function _update_8000_field_create_field(array &$field_config) {
   $uuid = new Uuid();
 
   // Merge in default values.
-  $field += array(
-    'id' => $field['field_name'],
+  $field_config += array(
     'uuid' => $uuid->generate(),
     'entity_types' => array(),
     'cardinality' => 1,
@@ -32,7 +34,7 @@ function _update_7000_field_create_field(&$field) {
   );
 
   // Set the storage.
-  $field['storage'] = array(
+  $field_config['storage'] = array(
     'type' => 'field_sql_storage',
     'module' => 'field_sql_storage',
     'active' => TRUE,
@@ -40,31 +42,31 @@ function _update_7000_field_create_field(&$field) {
   );
 
   // Save in config.
-  Drupal::config('field.field.' . $field['id'])
-    ->setData($field)
+  Drupal::config('field.field.' . $field_config['id'])
+    ->setData($field_config)
     ->save();
-  update_config_manifest_add('field.field', array($field['id']));
+  update_config_manifest_add('field.field', array($field_config['id']));
 
   // Create storage for the field. This requires a field entity, but cannot use
   // the regular entity_create() function here.
-  $field_entity = new Field($field);
+  $field_entity = new Field($field_config);
   field_sql_storage_field_storage_create_field($field_entity);
 }
 
 /**
- * Deletes a field stored in SQL storage directly from the database.
+ * Deletes a field directly from configuration.
  *
  * To protect user data, this function can only be used to delete fields once
  * all information it stored is gone. Delete all data from the
  * field_data_$field_name table before calling by either manually issuing
- * delete queries against it or using _update_7000_field_delete_instance().
+ * delete queries against it or using _update_8000_field_delete_instance().
  *
- * @param $field_name
+ * @param string $field_name
  *   The field name to delete.
  *
  * @ingroup update_api
  */
-function _update_7000_field_delete_field($field_name) {
+function _update_8000_field_delete_field($field_name) {
   $table_name = 'field_data_' . $field_name;
   if (db_select($table_name)->range(0, 1)->countQuery()->execute()->fetchField()) {
     $t = get_t();
@@ -73,8 +75,8 @@ function _update_7000_field_delete_field($field_name) {
   // Delete all instances.
   $config_names = config_get_storage_names_with_prefix('field.instance');
   foreach ($config_names as $id) {
-    list($p1, $p2, $entity_type, $bundle, $field_name) = explode('.', $id);
-    if ($field_name == $field_name) {
+    list(, , $entity_type, $bundle, $config_field_name) = explode('.', $id);
+    if ($config_field_name == $field_name) {
       update_config_remove_config('field.instance', $entity_type . '.' . $bundle . '.' . $field_name);
     }
   }
@@ -88,13 +90,20 @@ function _update_7000_field_delete_field($field_name) {
 }
 
 /**
- * Deletes an instance and all its data of a field stored in SQL Storage.
+ * Deletes an instance and all its data of a field stored in configuration.
  *
  * BEWARE: This function deletes user data from the field storage tables.
  *
+ * @param string $field_name
+ *   The name of the field.
+ * @param string $entity_type
+ *   The name of the entity type.
+ * @param $bundle
+ *   The name of the bundle.
+ *
  * @ingroup update_api
  */
-function _update_7000_field_delete_instance($field_name, $entity_type, $bundle) {
+function _update_8000_field_delete_instance($field_name, $entity_type, $bundle) {
   // Delete field instance configuration data.
   update_config_remove_config('field.instance', $entity_type . '.' . $bundle . '.' . $field_name);
 
@@ -110,7 +119,7 @@ function _update_7000_field_delete_instance($field_name, $entity_type, $bundle)
 }
 
 /**
- * Fetches all of the field definitions from the database.
+ * Fetches all of the field definitions from configuration.
  *
  * Warning: Unlike the field_read_fields() API function, this function returns
  * all fields by default, including deleted and inactive fields, unless
@@ -132,18 +141,17 @@ function _update_7000_field_read_fields(array $conditions = array(), $key = 'id'
   $matching_fields = array();
 
   $config_names = config_get_storage_names_with_prefix('field.field');
-  $deleted_fields = Drupal::state()->get('field.field.deleted') ?: array();
-  // Ditch UUID keys, we will iterate through deleted fields using a numeric
-  // index.
-  $deleted_fields = array_values($deleted_fields);
+  $config_names += Drupal::state()->get('field.field.deleted') ?: array();
 
-  if (empty($config_names) && empty($deleted_fields)) {
-    return $matching_fields;
+  if (empty($config_names)) {
+    return array();
   }
 
   // Collect matching fields.
-  foreach ($config_names as $id) {
-    $field = config($id)->get();
+  foreach ($config_names as $field) {
+    if (!is_array($field)) {
+      $field = config($field)->get();
+    }
 
     if (!empty($conditions)) {
       foreach ($conditions as $key => $value) {
@@ -162,19 +170,23 @@ function _update_7000_field_read_fields(array $conditions = array(), $key = 'id'
 /**
  * Writes a field instance directly to configuration.
  *
+ * @param array $field_config
+ *   An array of field properties.
+ * @param array $instance
+ *   An array of field instance properties.
+ *
  * @ingroup update_api
  */
-function _update_7000_field_create_instance($field, &$instance) {
+function _update_8000_field_create_instance(array $field_config, array &$instance_config) {
   $uuid = new Uuid();
 
   // Merge in defaults.
-  $instance += array(
+  $instance_config += array(
     'description' => '',
     'required' => FALSE,
-    'id' => $instance['entity_type'] . '.' . $instance['bundle'] . '.' . $instance['field_name'],
     'uuid' => $uuid->generate(),
-    'field_uuid' => $field['uuid'],
-    'field_type' => $field['type'],
+    'field_uuid' => $field_config['uuid'],
+    'field_type' => $field_config['type'],
     'default_value' => array(),
     'default_value_function' => '',
     'settings' => array(),
@@ -184,10 +196,10 @@ function _update_7000_field_create_instance($field, &$instance) {
   );
 
   // Save in config.
-  Drupal::config('field.instance.' . $instance['id'])
-    ->setData($instance)
+  Drupal::config('field.instance.' . $instance_config['id'])
+    ->setData($instance_config)
     ->save();
-  update_config_manifest_add('field.instance', array($instance['id']));
+  update_config_manifest_add('field.instance', array($instance_config['id']));
 }
 
 /**
diff --git a/core/modules/user/user.install b/core/modules/user/user.install
index 68f51a5..d0ca5ef 100644
--- a/core/modules/user/user.install
+++ b/core/modules/user/user.install
@@ -709,7 +709,7 @@ function user_update_8011() {
 
   // Create the field and instance.
   $field = array(
-    'field_name' => 'user_picture',
+    'id' => 'user_picture',
     'module' => 'image',
     'type' => 'image',
     'cardinality' => 1,
@@ -720,10 +720,10 @@ function user_update_8011() {
       'default_image' => FALSE,
     ),
   );
-  _update_7000_field_create_field($field);
+  _update_8000_field_create_field($field);
 
   $instance = array(
-    'field_name' => 'user_picture',
+    'id' => 'user.user.user_picture',
     'entity_type' => 'user',
     'label' => 'Picture',
     'bundle' => 'user',
@@ -749,7 +749,7 @@ function user_update_8011() {
       'weight' => -1,
     ),
   );
-  _update_7000_field_create_instance($field, $instance);
+  _update_8000_field_create_instance($field, $instance);
 
   // Assign display settings for the 'default' and 'compact' view modes. In D7,
   // user pictures did not require Image module to work. Image module only