Rails 7.2 to 8.1 Upgrade: What Actually Breaks and How to Fix It

Rails 8 wants you to drop Redis, Sprockets, and Sidekiq and adopt a full stack of database-backed infrastructure. None of that is mandatory yet, although the gap between the blessed stack and yours widens with every minor release.&#xA;The Rails 7.2 to 8.1 upgrade itself is one of the smoother major version jumps in recent Rails history, with fewer hard removals and fewer gotchas that prevent the…