diff --git a/admin/tool/uploaduser/index.php b/admin/tool/uploaduser/index.php
index 9a6a1042c62..384a900c7c6 100644
--- a/admin/tool/uploaduser/index.php
+++ b/admin/tool/uploaduser/index.php
@@ -527,6 +527,16 @@ if ($formdata = $mform2->is_cancelled()) {
                             }
                         }
 
+                        if ($column === 'lang') {
+                            if (empty($user->lang)) {
+                                // Do not change to not-set value.
+                                continue;
+                            } else if (clean_param($user->lang, PARAM_LANG) === '') {
+                                $upt->track('status', get_string('cannotfindlang', 'error', $user->lang), 'warning');
+                                continue;
+                            }
+                        }
+
                         if (in_array($column, $upt->columns)) {
                             $upt->track($column, s($existinguser->$column).'-->'.s($user->$column), 'info', false);
                         }
@@ -682,6 +692,13 @@ if ($formdata = $mform2->is_cancelled()) {
                 $upt->track('email', get_string('invalidemail'), 'warning');
             }
 
+            if (empty($user->lang)) {
+                $user->lang = '';
+            } else if (clean_param($user->lang, PARAM_LANG) === '') {
+                $upt->track('status', get_string('cannotfindlang', 'error', $user->lang), 'warning');
+                $user->lang = '';
+            }
+
             $forcechangepassword = false;
 
             if ($isinternalauth) {