diff --git a/core/modules/file/file.js b/core/modules/file/file.js
index 1071384..050b4b9 100644
--- a/core/modules/file/file.js
+++ b/core/modules/file/file.js
@@ -66,6 +66,9 @@ Drupal.file = Drupal.file || {
    */
   validateExtension: function (event) {
     // Remove any previous errors.
+    if (!this.value) {
+      return false;
+    }
     $('.file-upload-js-error').remove();
 
     // Add client side validation for the input[type=file].