For those of you who are rooted and getting errors -- make sure if you froze any bloat that you defrost it. The update checks for that stuff and will fail if it doesn't find it. If you deleted apps instead of freezing, hopefully you took a nandroid backup before that you can restore. Otherwise you may be in trouble.
Also make sure you are using the stock recovery, not Bootstrap or Safestrap recoveries. You can still get into stock recovery the standard way after installing Bootstrap or Safestrap.
If you're on
5.7.893 then yes, you will need to roll back before you can update. For those who installed the 5.9.901 leak, there is a separate, smaller update floating around that will update you straight to .902. Check post #38 of this thread for more info.