When loading Buildcraft 6.1.8 a NoSuchMethodError in API.

Yes, DragonAPI built the crash, thanks. I know, I don't have put the crash, but I've lost it ...

without a crashlog we can't help you with this but most of the time this is caused by another mod being installed that still ships an older BC api

Yeah, BuildCraft has been undergoing a bunch of changes lately. Which other mods do you have at present? Could you post the whole crashlog?

I know that DragonAPI caused this sort of crash for me just yesterday, because it still uses an outdated version of the Buildcraft API.