Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/53257cc9342a8fa9b58cae2b49b7b5a8.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563