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Issue description:

Steps to reproduce:

1.install all mods in crash log
2.run server
3.

Version (make sure you are on the latest version before reporting):

Forge: forge-1.12.2-14.23.2.2611
Mekanism: 1.12.2-9.4.3.330
SpongeForge1.12.2-2611-7.1.0-BETA-2990

If a (crash)log is relevant for this issue, link it here: (It's almost always relevant)

crash log
https://pastebin.com/raw/shBSwwxG

Either someone is packaging an un-reobfed api (which they shouldn't be packaging in any form), or Sponge is doing some stupid things...

Please try removing mods (including Sponge) until the error stops.

If you mean Mekanism-1.12.2-9.4.3.330-api.jar then just delete it, its for dev workspaces only

Everything worked when I removed Mekanism API, so maybe Sponge doesn’t like Mek API
Haven’t tried on a plain forge server yet.
As far as I know, this causes a crash on client as well.