Just did that, and after i removed Minechem i could create the world and play, tried to add it afterwards, but it crashes 10-15 secs after world loading.
You people are angels.so minechem may just need to be updated it sounds like cause i have had it in packs recently on the new fluid api and it works fine.
Now I don't have to do the digging myself; I can go about fixing it. I don't think that you should be crashing once the world starts; that's something else... Which I'll test. I've been able to log into worlds with minechem, as have other people, especially on Harvest's server (which runs the update and an old world). It could just be a memory/video setting thing.
I'll get to the bugfix as soon as I can, but no promises. I have some other plans for the next update, including the removal of Coppertools, which will be obseletized by Project Red. They're finally adding gem armors.