So I found a curse mod pack called expedition and wanted to try it out. I put a decent amount of hours into it but all of a sudden no matter what I do minecraft crashes when I make a new world or try to join a existing world. It crashes on the "loading world" screen every time. The first time it started doing this, the error report was "Exception in server tick loop java.lang.NoClassDefFoundError" and then the mod Elec Core so I thought that was the problem and deleted all the Elec 332 mods that were in the pack. Then I started up minecraft and the same error came up only instead of Elec Core mods coming up Open Blocks came up. I deleted all Open Mods, started the game, and with no luck the same error report came up with gravestone being the mod in question. It seems that every time I try to join a world the same error comes up with a different mod. Can anyone fix this?