Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/c3dc56e67af24e95e4a35d0c6c1da126.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563