Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/70609b048d72f4d6f81a92b6a14b2f4e.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563