diff --git a/user/profile/lib.php b/user/profile/lib.php
index f7d0d8899a3de..c82551f99c1ec 100644
--- a/user/profile/lib.php
+++ b/user/profile/lib.php
@@ -185,6 +185,10 @@ public function edit_save_data($usernew) {
         $data = new stdClass();
 
         $usernew->{$this->inputname} = $this->edit_save_data_preprocess($usernew->{$this->inputname}, $data);
+        if (!isset($usernew->{$this->inputname})) {
+            // Field cannot be set to null, set the default value.
+            $usernew->{$this->inputname} = $this->field->defaultdata;
+        }
 
         $data->userid  = $usernew->id;
         $data->fieldid = $this->field->id;