Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/e3b22a3a5c242201de4221bc6e0d1e20.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563