Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/ee2ce2b19f2b0ee8deb68bd8bb5ec38f.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563