Factorio Forums

When applying an upgrade planner, either to the world or to a blueprint, a warning should be displayed if doing so will cause underground belts to break.

More specifically:

• An underground 'breaking' is defined as any change in what underground connects to what:
  • Pair of undergrounds that previously connected no longer connect because you're downgrading them to tier that doesn't have enough reach for the gap? That's a break.
  • Pair of undergrounds that previously connected no longer connect because you upgraded one but not the other? I don't think the current version of the upgrade planner allows you to do that, but if it did, that would be a break.
  • Underground that changes which other underground it pairs with, because the new partner was previously a different tier but is now the same tier and closer than the original one? That's a break.
  • Underground that previously connected to nothing now connects to something? That's a break.
• If applying an upgrade planner would cause any of these breaks, a warning is displayed, similar to the warning for trying to undo an action more than a minute old. This warning must identify exactly which undergrounds will break, and how, and, for upgrades affecting a large area, must allow the player to zoom in to see what exactly is the problem and where
• The player has the option to either proceed with the upgrade, to leave the broken undergrounds unaffected but proceed with the rest of upgrade, or cancel it entirely
  • Optional stretch goal: on the warning screen, the player can right-click individual undergrounds to exclude them from the upgrade, just like excluding buildings from a blueprint, then proceed with upgrading everything else. The player should be able to exclude any affected underground, not just the ones the game thinks are broken.
  • Optional stretch goal: the player has the option to proceed with the upgrade, but to have all the 'broken' undergrounds marked in some way, so they can go there and fix it manually; these marks remain until the underground in question is remove or replaced, or until manually dismissed

Rational: It is really annoying when I downgrade my 8-8 balancer from blue belts to red, only to discover later that half the outputs aren't working because some of the undergrounds required blue-belt length, or try to upgrade an assembler farm to faster belts for higher throughput only to find that my belt weaving isn't woven no more.