Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/de72f0ae9fb4ff7d0cbe86b2df9f9085.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563