Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/30eb9c3f1d1d2b1c16da4c55fc6a5270.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563