Измените

 

Warning: imagepng(/var/www/mojaopstina.rs/www-root/public/images/captcha/30a8d9d37b58678de3a7a6953cd4dca6.png): failed to open stream: Permission denied in /var/www/mojaopstina.rs/www-root/library/Zend/Captcha/Image.php on line 563