I have a private server running Yao Pack, and I added ICBM-classic-1.12.2-4.0.1b20200328215453.
The thing is whenever I put a Launcher Support Frame T3 in the world, it starts looping error messages and effectively DoSes the server.
The fix is to backup to a point prior to plomping down the frame.
I have not tried the T1 and T2 frames nor other blocks of the mod.

Pastebin of the crash log (cut so it would fit pastebin, but contains error loop):
https://pastebin.com/ShQasm36

Thank you very much for your time and hope it is an easy fix!

EDIT: Every block from this mod that you can put down breaks the server, tested it today.

Does it break if you place down any other blocks from other mods that accept ic2 energy? (especially non-ic2 blocks)