Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/f83e21a20365090a8e49e46592f7f1eb.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563