Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/2d3ed167eb3a7a3d9f7b2d5493c8be90.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563