bookstack/resources/lang/en/passwords.php

<?php
/**
 * Password Reminder Language Lines
 * The following language lines are the default lines which match reasons
 * that are given by the password broker for a password update attempt has failed.
 */
return [

    'password' => 'Passwords must be at least eight characters and match the confirmation.',
    'user' => "We can't find a user with that e-mail address.",
    'token' => 'The password reset token is invalid for this email address.',
    'sent' => 'We have e-mailed your password reset link!',
    'reset' => 'Your password has been reset!',

];