Your systems is already down, rolling back is the same thing, if not more effort than rolling forward. At least that's what I've always found.

Another option is to have customers point at stage after it has been upgraded and if it all goes horribly wrong, a load balancer change should be enough to point people back at the older production environment.

All this being said, problems in production shouldn't be a thing with configuration management, infrastructure as code (Terraform), and tests, not to mention three environments (development,test, stage - at minimum) to work your way through before pushing to production.