Thats easy to fix, update your Trident (Server and client of course) to 1.2.0 and update to the newest Cauldron version ( this error only happens if u use cauldron... ) and your problem is fixed.
The newest version is kCauldron 1448.121 (Same forgeversion as 1.2.0 trident)
If you dont want to update, just delete the Mod "EnderStorage" from your server or delete Cauldron or use an older version of Cauldron (cauldron-1.7.10-1.1236.05.212 worked for me).
That would fix it for 1.1.0 and 1.0.0, but i really recommend to just update Trident to 1.2.0, it fixes alot of such errors.
It appers because Forge has changed some stuff on the Fluid API afaik, and EnderStorage still uses the old one...hope it helps
I opened up this pack on single player creative to look around a little, and i discovered a entity 2 blocks tall, labeled MissingName. I could not harm it, but it was visible in the minimap as a player. I want to know what it is and what it does.