How To Unmarked url for xf 2.1.x fixed unicode (no addon)

[thxf.org thxf.org is verified member.]

The URL does not signify that you should edit the addon so you don't need to do anything (personal experience).
This code I have added some unicode characters when the member using unicode combination will fail to delete the

Find Router file. php in / src / XF / Mvc directory

Find the code

if ($romanize)
        {
            $string = utf8_romanize(utf8_deaccent($string));
            $originalString = $string;

            // Attempt to transliterate remaining UTF-8 characters to their ASCII equivalents
            $string = @iconv('UTF-8', 'ASCII//TRANSLIT', $string);
            if (!$string)
            {
                // iconv failed so forget about it
                $string = $originalString;
            }
        }

add below

$aPattern = array (
            "a" => "á|à|ạ|ả|ã|ă|ắ|ằ|ặ|ẳ|ẵ|â|ấ|ầ|ậ|ẩ|ẫ|Á|À|Ạ|Ả|Ã|Ă|Ắ|Ằ|Ặ|Ẳ|Ẵ|Â|Ấ|Ầ|Ậ|Ẩ|Ẫ",
            "o" => "ó|ò|ọ|ỏ|õ|ô|ố|ồ|ộ|ổ|ỗ|ơ|ớ|ờ|ợ|ở|ỡ|Ó|Ò|Ọ|Ỏ|Õ|Ô|Ố|Ồ|Ộ|Ổ|Ỗ|Ơ|Ớ|Ờ|Ợ|Ở|Ỡ",
            "e" => "é|è|ẹ|ẻ|ẽ|ê|ế|ề|ệ|ể|ễ|É|È|Ẹ|Ẻ|Ẽ|Ê|Ế|Ề|Ệ|Ể|Ễ",
            "u" => "ú|ù|ụ|ủ|ũ|ư|ứ|ừ|ự|ử|ữ|Ú|Ù|Ụ|Ủ|Ũ|Ư|Ứ|Ừ|Ự|Ử|Ữ",
            "i" => "í|ì|ị|ỉ|ĩ|Í|Ì|Ị|Ỉ|Ĩ",
            "y" => "ý|ỳ|ỵ|ỷ|ỹ|Ý|Ỳ|Ỵ|Ỷ|Ỹ",
            "d" => "đ|Đ",
            "" => "̉|̣|̃|̀|́", // dấu unicode tổ hợp
        );
        while(list($key,$value) = each($aPattern))
        {
            $string = preg_replace('/'.$value.'/i', $key, $string);
        }

Note in the admincp it will tell the file to be changed, don't worry about it