Forge: 1.12.2-14.23.5.2836-universal
OpenBlocks: 1.12.2-1.8.1
Mekanism: 1.12.2-9.7.4.375
Mekanism Generators: 1.12.2-9.7.4.375

Crash Log: https://pastebin.com/6Vdt81DF

"That's the XP Drain's issue - they're giving us an invalid FluidStack, seems it's missing a Fluid name or they're giving a Fluid that's not the chosen one from the registry."
-Mekanism Dev
Link: mekanism/Mekanism#5552**

Crash happened on a server. Placed XP Drain on top of a Mekanism Basic Fluid Tank and standing on top of it crashed the server.

Similar to #944. I wasn't able to reproduce it with just OpenBlocks and Cyclic (other mod that registers liquid under same id), so I'm suspecting some other mod is messing with registries. Can you attach you 'debug.log' (big file, use pastebin or something similar) after it crashes?

Also, is this issue reproducible on local, freshly created world with same config and set of mods?

Closing, since it does not seem like problem with OpenBlocks. See #977 for details.