Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/eb38e974b0c9aa73b1427da76b8b2e6c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563