I have a childhood memory of my dad buying a shrink-wrapped copy of the Windows 3.1 Upgrade that was supposed to allow any installation of "3.0 or earlier" to become Win 3.1. it turned out when we actually tried it it only accepted 3.x though. [1]

I think he ended up pirating a 3.x install from a friend and running the upgrade on to of that; felt pretty morally clear given what the box had advertised.

[1]: eg https://www.ebay.com/itm/376080245422