I have kerbol plus, which includes Kopernicus, so imagine that coudl be it (not tested yet). Even with build time for KSC upgrades turned off the problem persists in that upgrade don't actually happen (but the funds bug does not appear). Looking at the KCT code it is the FacilityUpgradedEvent that keeps getting called (in the case of instant upgrades being disabled) because the line: KCT_Utilities.AddFunds(listBuilding.cost, TransactionReasons.None); Must be the one that is causing the funding to keep going up. Note sure why Kopernicus would interfere with this though! I'll try uninstalling Kopernicus to confirm. I can see how the alternative of overriding the upgrade button would be more 'invasive', but maybe a more elegant solution. Just to check it's nothing to do with KSP storing upgrade levels as 0.5 instead of whole numbers (I presume not as you record the upgrade info in a KCT specific object)? - - - Updated - - - Quoting myself, sign of madness? Anyway I can confirm Kopernicus seems to be the source of this particular clash - upgrading works fine without it. I've had a quick scan of the Kopernicus code, but it's too clever for me, I will ask on that thread and see if anyone has an idea what might be causing it.