Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1b8eb7e5a9aa99f09d603422a2718627.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563