diff -u b/core/modules/file/file.field.inc b/core/modules/file/file.field.inc
--- b/core/modules/file/file.field.inc
+++ b/core/modules/file/file.field.inc
@@ -403,7 +403,7 @@
  * This validator is used only when cardinality not set to 1 or unlimited.
  */
 function file_field_widget_multiple_count_validate($element, &$form_state, $form) {
-  $parents = $element['#array_parents'];
+  $parents = $element['#parents'];
   $values = NestedArray::getValue($form_state['values'], $parents);
 
   array_pop($parents);
@@ -433,7 +433,7 @@
       'warning'
     );
     $values['fids'] = array_slice($values['fids'], 0, $keep);
-    NestedArray::setValue($form_state['values'], $element['#array_parents'], $values);
+    NestedArray::setValue($form_state['values'], $element['#parents'], $values);
   }
 }
 
@@ -601,7 +601,7 @@
   $langcode = $element['#language'];
   $parents = $element['#field_parents'];
 
-  $submitted_values = NestedArray::getValue($form_state['values'], array_slice($button['#array_parents'], 0, -2));
+  $submitted_values = NestedArray::getValue($form_state['values'], array_slice($button['#parents'], 0, -2));
   foreach ($submitted_values as $delta => $submitted_value) {
     if (empty($submitted_value['fids'])) {
       unset($submitted_values[$delta]);
@@ -612,10 +612,15 @@
   // them, as we display each file in it's own widget.
   $new_values = array();
   foreach ($submitted_values as $delta => $submitted_value) {
-    foreach ($submitted_value['fids'] as $fid) {
+    if (is_array($submitted_value['fids'])) {
+      foreach ($submitted_value['fids'] as $fid) {
+        $new_value = $submitted_value;
+        $new_value['fids'] = array($fid);
+        $new_values[] = $new_value;
+      }
+    }
+    else {
       $new_value = $submitted_value;
-      $new_value['fids'] = array($fid);
-      $new_values[] = $new_value;
     }
   }
 
@@ -623,7 +628,7 @@
   $submitted_values = array_values($new_values);
 
   // Update form_state values.
-  NestedArray::setValue($form_state['values'], array_slice($button['#array_parents'], 0, -2), $submitted_values);
+  NestedArray::setValue($form_state['values'], array_slice($button['#parents'], 0, -2), $submitted_values);
 
   // Update items.
   $field_state = field_form_get_state($parents, $field_name, $langcode, $form_state);
diff -u b/core/modules/file/file.module b/core/modules/file/file.module
--- b/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -1008,8 +1008,6 @@
  * This function is assigned as a #value_callback in file_element_info().
  */
 function file_managed_file_value(&$element, $input = FALSE, $form_state = NULL) {
-  $fids = array();
-
   // Find the current value of this field.
   $fids = !empty($input['fids']) ? explode(' ', $input['fids']) : array();
   foreach ($fids as $key => $fid) {
@@ -1185,8 +1183,8 @@
  *   The FAPI element whose values are being saved.
  *
  * @return
- *   The file entity representing the file that was saved, or FALSE if no file
- *   was saved.
+ *   An array of file entities for each file that was saved, keyed by its file
+ *   ID, or FALSE if no files were saved.
  */
 function file_managed_file_save_upload($element) {
   $upload_name = implode('_', $element['#parents']);