Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f1e5d0b84667eb18c630e6e49be9c88a.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563