Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/80b8e7fa3fc4d6337bd8696fe9a4f451.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563