I was in the middle of a hot lap near the finish line and up on my best when the screen goes black and tells me Forza needs an update.
So much for my hot lap… ok go ahead and update.
So it downloads and starts installing gets to 97% and has been at 97% for several minutes now without progressing.
Not sure what to do at this point
Press the Big X button to put the screen as the main one of the desktop, then leave it alone. DO NOT interrupt the download. It will finish eventually.
The download appears to have completed fairly quickly, there is nothing in the que
It started to install and was progressing normally until it got to 97% and now it is just staying at 97%
The update just arrived here. If you’re still stuck, do the full console reset:
1 – from the Dashboard, out of all games, hold the X button on the front of the console down until it shuts the system down.
2 – Disconnect the external power from the wall plug (or at least disconnect the wall-side connector on the power pack itself.
3 – WAIT until all power drains from the external power pack (no light, either white or dull orange showing on the pack).
4 – Reconnect the power supply to the electrical outlet.
5 – Restart the console in the usual manner, i.e., either with the controller or a short push on the X button on the front of the X1.
6 – WAIT until the console self-checks and fully boots to the Dashboard before attempting anything.
If you don’t disconnect the external power pack and let the power completely drain out, the system is still retaining “old” stuff and not resetting. When you come back in, check My games & apps to make sure the Queue has cleared. That would indicate the full update finished properly. Then launch the game.
Do we have to do this, as my game started even with the blue update bar saying it was still at 97%?
After waiting a while longer I saw on another site that someone else had had the same problem and was able to start the game from the games menu so I select one of my friends who was in the game and it brought up an option to play from there. I canceled out of that then went back to the home screen and there was no longer the updating message.
Something definitely appeared to have been stuck and if I had just left it alone I think it may have still said 97% 5 hours from now.
Anyway looks like I am good to go now aside from it blowing my hot lap on me
Yes. I saw the notice at the bottom, too, but when I have received a download (or even DLC), I always make sure the queue is cleared, and then do the hard reboot as I described here, to make sure everything is proper. I go back to the old days of PCs - shut everything down when updating, including the AV program. After the download, reboot the PC. 
It might be overkill, but my system is working as it should and I want to keep it that way. I do NOT slam into the game when a download reaches the “Ready to play” notice. Only after the queue has cleared. Then I restart (hard reboot), sign into Live again and then play.
Cheers snowy I don’t usually rush in either, don’t know why I did TBH. Did it your way anyway just to be on the safe side.
Are you not a mod anymore then?
I’m still what I’ve been for the last eight or nine years. Here, there and everywhere.
Yeah I would say that the reboot or in this case cold boot is overkill for sure but it never hurts.
Why would you get a game update alert in the middle of a session? An update alert only pops up as you’re launching the game. Maybe I’ve never experienced this as I keep my console on Energy Saving?
Anyway, hope your issue’s resolved.
Oh, I’ve tried the pause and resume trick and updates start to download. This has happened on occasions, where I’d start a download and nothing happens for a while… I pause and resume… boom, it works!
As for in-game updates, I’d recommend you disable that feature and let the game update in the dash while you do other stuff on your console or just put it on stand by until it finishes downloading. I’ve read many many times on this forum and others, that you should not be playing games while they are updating or installing.