I have a PRC connected to an Enrichment Chamber and a Restrictive Transporter connected to a chest as shown below.

All the HDPE Pellets are going to the chest and causing this error message.

[12:30:05] [Server thread/FATAL]: Error executing task java.util.concurrent.ExecutionException: java.lang.NullPointerException at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_25] at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_25] at net.minecraft.util.Util.func_181617_a(SourceFile:46) [h.class:?] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:668) [MinecraftServer.class:?] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613) [MinecraftServer.class:?] at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:240) [bzl.class:?] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471) [MinecraftServer.class:?] at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25] Caused by: java.lang.NullPointerException [12:30:06] [Server thread/FATAL]: Error executing task

If I remove the Restrictive Transporter then it works correctly. The difference seems to be that the HDPE Pellets are going is sets instead of one at a time.

Thanks,

Do you have a full log? Because this log doesn't tell anything about where in Mekanism it could go wrong.

No sorry, this above extract was being generated every second, once for each pellet. The game wasn't crashing just that all the pellets were going down the restrictive pipe. Looks like a call back message. I can run the game again and give you the full log if it helps.

Cheers,

I'm afraid that log gives no detail of a bad Mekanism interaction. Let me know if you can isolate Mekanism in a crash log.

Would a 20 second video help to show what is happening? https://youtu.be/DSIj9FX7P6U