Happens whenever I attempt to connect fluix pipe to an essentia import bus. I assume it's because it attempts to render regardless of it being on the server or client. I tested it on singleplayer and it works as expected.

java.lang.RuntimeException: Error while adding thaumicenergistics.parts.AEPartEssentiaImportBus to event bus
at appeng.me.NetworkEventBus.readClass(NetworkEventBus.java:118)
at appeng.me.Grid.add(Grid.java:100)
at appeng.me.GridNode.setGrid(GridNode.java:426)
at appeng.me.GridConnection.(GridConnection.java:51)
at appeng.core.Api.createGridConnection(Api.java:96)
at appeng.parts.CableBusContainer.addToWorld(CableBusContainer.java:369)
at appeng.tile.networking.TileCableBus.onReady(TileCableBus.java:129)
at appeng.hooks.TickHandler.onTick(TickHandler.java:144)
at cpw.mods.fml.common.eventhandler.ASMEventHandler_318_TickHandler_onTick_TickEvent.invoke(.dynamic)
at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:51)
at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:122)
at cpw.mods.fml.common.FMLCommonHandler.onPostServerTick(FMLCommonHandler.java:247)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:574)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:414)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:670)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/renderer/RenderBlocks
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
at java.lang.Class.privateGetPublicMethods(Unknown Source)
at java.lang.Class.privateGetPublicMethods(Unknown Source)
at java.lang.Class.privateGetPublicMethods(Unknown Source)
at java.lang.Class.getMethods(Unknown Source)
at appeng.me.NetworkEventBus.readClass(NetworkEventBus.java:85)
... 14 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.renderer.RenderBlocks
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:188)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 21 more
Caused by: java.lang.RuntimeException: Attempted to load class ble for invalid side SERVER
at cpw.mods.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:50)
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:276)
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:174)
... 23 more

0.4.2a Should address this issue. Thank you for letting me know.