When I open a 1.12.2 world with Forge, I am unable to access chests, enderchests, or shulker boxes. Also, attempting to open enderchests causes my game to crash, with this error message:
The game crashed whilst unexpected error
Error: java.lang.AbstractMethodError: net.minecraft.block.state.BlockStateContainer$StateImplementation.doesSideBlockChestOpening(Lnet/minecraft/world/IBlockAccess;Lnet/minecraft/util/math/BlockPos;Lnet/minecraft/util/EnumFacing;)Z
I don't know if this was a problem with one of the mods I was using, or if it was a problem with Forge and Minecraft. The mods I was using are: Abyssalcraft, Vic's Modern Warfare, CustomNPCs, and Optifine.