Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/1485572373a7fc260c9c19d0b5b5e4e4.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563