Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/9ab8f154a20eda6335d647e00ab5d2f4.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563