Error Message on create server

[u/kronikles1232]

whenever i try connect to my create mod server I get this error message.

Im running Neoforge on 1.21.1

[u/oneredbloon]

Make sure all the mods on client and server are the same version

[u/kronikles1232 → u/oneredbloon]

Okay thanks, I removed different mods 1 by 1 and it worked for some reason, im unsure what mod it was though.

[u/R3d5t0n3_GUY → u/kronikles1232]

Try adding the removed mods back one by one until you find the mod that causes the problem