Warning (2) : Undefined array key "HTTP_ACCEPT_LANGUAGE" [in /home/w-bdash/www/public_html/src/Controller/AppController.php, line 67]
Warning (512) : Unable to emit headers. Headers sent in file=/home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php line=37 [in /home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 65]
Warning (2) : Cannot modify header information - headers already sent by (output started at /home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 159]
Warning (2) : Cannot modify header information - headers already sent by (output started at /home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /home/w-bdash/www/public_html/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 192]
Error: substr(): Argument #1 ($string) must be of type string, null given

substr(): Argument #1 ($string) must be of type string, null given 📋

TypeError
Error in: APP/Controller/AppController.php, line 67
APP/Controller/AppController.php at line 67 (edit)
        }
        
        if(!$this->session->check("locale"))
        {
            switch(substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 02))
            {
                case "ja":
                    I18n::setLocale('ja');
                    break;

If you want to customize this error message, create templates/Error/error500.php