When the token is greater than 100 characters the error occurs.
this happens if the user id is high.
My solution was to replace
// $ur_token = str_split ($_GET[‘ur_token’], 50);
$ur_token [1] = substr($_GET[‘ur_token’], 50, strlen ($_GET[‘ur_token’]));
at line 280 of file class-ur-email-confirmation.php
