Warning (2) : chmod(): No such file or directory [in /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Cache/Engine/FileEngine.php, line 397]
Warning (512) : Could not apply permission mask "/home/live1000/domains/ugreenbinhduong.com/public_html/tmp/cache/data/phinx_log_all_" on cache file "436" [in /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Cache/Engine/FileEngine.php, line 402]
Warning (512) : Unable to emit headers. Headers sent in file=/home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php line=36 [in /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 71]
Warning (2) : Cannot modify header information - headers already sent by (output started at /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:36) [in /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 168]
Warning (2) : Cannot modify header information - headers already sent by (output started at /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:36) [in /home/live1000/domains/ugreenbinhduong.com/public_html/web4s/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 197]
Error: Could not start the session, headers already sent in file `CORE/src/Error/Renderer/HtmlErrorRenderer.php` on line `36`

Could not start the session, headers already sent in file CORE/src/Error/Renderer/HtmlErrorRenderer.php on line 36 📋

Cake\Core\Exception\CakeException
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        $request $this->controller->getRequest();
        $lang $request->getSession()->read(LANG_FRONTEND);        
        if(empty($lang)){
            $lang TableRegistry::get('Languages')->getDefaultLanguage();
            $request->getSession()->write(LANG_FRONTEND$lang);
        }
    
        return $lang;
    }

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