Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/b05c1a7a30da95c5fa2a21a6eb43b47c.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563