my firewall 40F have future version in firmware but regularly asking for update why?

Hi @PK777 - Perhaps the auto-update is enabled in your settings, similar to this: 

https://docs.fortinet.com/document/fortigate/7.4.3/administration-guide/547335/automatic-updates

So, even if there are no updates available at that time or day, it will still check. To avoid this, you might want to review your settings again and adjust the frequency if necessary.