Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/ff0ae6a6cde9d1b96053a5c661f0d544.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563