How long does it take to update to macOS High Sierra on a desktop? Do you get a message that it is done?

It never takes that long on any of my Macs. They are usually finished upgrading in more like half an hour at the most.

If they ever took a couple of hours, I would certainly start troubleshooting to find out why.

The size of these files which get downloaded by the installer can take many hours

and the time span depends on several factors. None the least whether or not your

internet connection locally is dependent on wi-fi or if your Mac can use Ethernet.

..Plus the speed of your internet service provider to your hardware..

{Another question: one can assume when you choose to upgrade a fully new OS

would be if any applications you already have in the older existing system can be

upgraded as well. Some expensive third-party professional applications cannot be

or if they could, will cost you to get the later version. And there are times when an

upgrade is not the better way if you haven't investigated these potential issues. As

newer version of software may not have features you'd need to continue a project.}

In any event...

Good luck & happy computing! 🙂

Which desktop?

After the installer finishes, the Mac reboots.

It can take up to a couple of hours or so. Yes, it is obvious when it is done.

Mine either, However, I have seen a few posts on here where it did. So I tend to mention the worst case scenario. Better safe than sorry kind of logic.