Updated Immersive Engineering. Blast furnaces were not making steel.
Server crashed (by Jesse as usual ). Updated some of the mods to resolve. But it caused significant world corruption. Mostly in Botania blocks. Some really odd things like leaves becoming doors, tree trunks becoming forestry rain tanks, oil set ablaze, missing blocks entirely, flowers becoming metamorphic rocks. I deleted most of the chunks with MCEdit, and let it regenerate. That won't fix anything you've made though, sorry. Let me know if something you worked on broke and I'll try to help you repair it. –xilcoy