Authentication

Hi All,

I have setup new moodle instance and when i configured LDAP i am getting this error, did any one faced this issue.

Scheduled task failed: LDAP users sync job (auth_ldap\task\sync_task),Error writing to database
Debug info:
Duplicate entry '1-' for key 'mdl_tmpextu_mneuse_uix'
INSERT INTO mdl_tmp_extuser (username,mnethostid) VALUES(?,?)
[array (
  0 => '',
  1 => '1',
)]
Backtrace:
* line 1259 of \lib\dml\mysqli_native_moodle_database.php: call to moodle_database->query_end()
* line 1050 of \auth\ldap\auth.php: call to mysqli_native_moodle_database->insert_record_raw()
* line 728 of \auth\ldap\auth.php: call to auth_plugin_ldap->ldap_bulk_insert()
* line 50 of \auth\ldap\classes\task\sync_task.php: call to auth_plugin_ldap->sync_users()
* line 141 of \lib\cronlib.php: call to auth_ldap\task\sync_task->execute()
* line 249 of \lib\cronlib.php: call to cron_run_inner_scheduled_task()
* line 91 of \admin\tool\task\schedule_task.php: call to cron_run_single_task()