This issue manifests as NullPointerExceptions in the client Forge logs. The game client keeps running.
The problem only appears in multiplayer, I couldn't reproduce it in single player.

There are several NullPointerExceptions logged when placing the following blocks in the world on a Forge multiplayer server:

• Generator
• Sluice
• Advanced Sluice

When using the Advanced Sluice in combination with a rotor and generator (as described in the in-game books), logs show huge number of NullPointerExceptions causing the log files to have a huge size. (This is how I discovered the problem.)

Using the standard Sluice does not cause this problem. However the exceptions when placing the block in the world still remain.

The issue can be reproduced in the current latest 1.7.10 version of Forge (1566) as well as earlier versions using Mariculture 1.2.4.2a and Enchiridon 2.0.2a. The exceptions only appear in the client logs and don't show up in the server logs.

I tested the problem on multiple versions of 1.7.10 Forge server and client with only these two mods with the same results.

I have uploaded logs, both were produced on a new server with Forge version 1566 and the mentioned mod versions.

For the first, I entered the world, placed a Sluice, a rotor and a Generator in the world (the water tower was preconstructed.) and started power generation.

• http://pastebin.com/LuePNkB4

For the second I repeated those steps, but with the Advanced Sluice. I had to cut the log short because of the size limit. Seems that the exception happens when the addEnergy() method is called, although the method seems to have worked fine using the simple Sluice.

• http://pastebin.com/PTzCkmVW