After the launcher is updated running modpacks started to give an error. None of the twitchmodpack not working. Here's the error I received: 

The game crashed whilst initializing game
Error: java.lang.IllegalArgumentException: Block: class erogenousbeef.bigreactors.common.multiblock.block.BlockMultiblockController has property: controller with invalidly named value: �dle

 Crash report attached.