I tried reverting to 0.17.6 in Steam, and I still get exactly the same error trying to load in this version.

EDIT: Uninstalling the game caused leftover files in the game folder. Deleting this folder and reinstalling fixed the issue.

When trying to load the game I last saved in 0.17.6-1, I get the following error message:


Error while applying migration: Base Mod: 2015-07-02_Factorio_0.12.0.lua

__base__/migrations/2015-07-02_Factorio_0.12.0.lua:18: attempt to index field 'combat-robot-damage-5' (a nil value)
stack traceback ...