You did not explain what happened except that it failed. That is the result and not the information that experienced Mac techs need to know.
You have been given excellent advice. Unfortunately, what you want is for someone to say, "Oh, just do ..."
We'd like to but we can't. Not because we don't know Macs but because we don't know what happened on yours. "It would not update and I had to erase my computer and restore from backup." isn't enough information.
Sorry. The only way anyone can do this online is for you to try it again and give a blow-by-blow account of how it failed. That means you try it, take notes as it happens and tell us exactly including any error messages and how long it took before you gave up.
BTW, it might work. High Sierra can take over an hour to install on a Mac with an SSD—a spinning hard drive can take a lot longer. There will be long periods of time where it looks like nothing is happening.
Or have an experienced tech do it.
Here's the blow by blow account which was basically given in the original thread.
I had OS Sierra on my computer
I downloaded High Sierra
I started the update
I left it updating for HOURS
I came back to find an error message saying it could not update and the only option was to "Restart"
After the restart, it immediately began trying to update again and would end up with the same error. Over and over.
The ONLY option to get it out of this was to FORCE the computer to shut down... which I did.
When it powered up after the forced shut down, it gave me an error that I can't remember, but the computer did not operate.
I then spoke with a technician and my option was to ERASE the computer, reload the original software and then update to Sierra. After updating to Sierra, I then restored from my Time Machine backup and the computer has worked with no issues since that time.
I like to have the latest operating system and my main question was "Can you upgrade to Mojave from Sierra"... So, NO, I do not want someone to say "Just do"
... I wanted to ask a simple question and avoid what happened when I tried to update previously. I have used Macs for 25 years, I am fully capable of figuring all of this out without your smart aleck responses.