Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/33218980e6aa5c63c8f1b2a1fdb24504.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563