Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/96c3eacd4e9d9037821f9c026fc8a60b.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563