Copying from the last time I responded to a roads update question and/or rant:
It's a bit of a pain to deal with right now for people with larger cities, but once it's over, you'll be able to save again.
As I understand it, the road model was upgraded to be more realistic (previously, roads with only shops or services on them never needed to be upgraded because they had no actual population, even though there should still have been traffic, etc). Then they added more "premium" roads so that your top choice of road wouldn't be a boring 6-lane blacktop.
So you sort of get hit from both sides. 1) You now need to upgrade those roads that you built for shops and services to more accurately reflect how much those roads would get used in a city, and 2) You were already at maximum density with the 6-lane roads, but now you're at maximum density and a couple of road upgrades behind.
Since requiring all of those roads to be upgraded as soon as the update came out would be really obnoxious, EA staggered the road upgrade requests to about one per day, and they'll continue until all of your roads are up to speed. It won't ask you to update the roads that don't yet need it, only the ones that are already behind. The good news is that you don't NEED to upgrade them right away. You can slow the process a little by leaving one red for as long as possible. Eventually a second one will pop up, but I think it takes longer than it would if you had immediately upgraded the first one.
