Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/2872c5f805f10799a0b3b783e80c8e69.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563