diff -u b/core/lib/Drupal/Core/Entity/Field/Type/Field.php b/core/lib/Drupal/Core/Entity/Field/Type/Field.php
--- b/core/lib/Drupal/Core/Entity/Field/Type/Field.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/Field.php
@@ -69,7 +69,7 @@
    */
   public function setValue($values) {
     // Support passing in only the value of the first item.
-    if (!is_array($values) || !is_numeric(current(array_keys($values)))) {
+    if (!is_array($values) || (!empty($values) && !is_numeric(current(array_keys($values))))) {
       $values = array(0 => $values);
     }