Not sure if anyone else has reported this, but I just recently updated to 224, and I get the following crash from my server:

http://pastebin.com/3sa9NCbU

If I downgrade to 216 (before the changelog seems to point at some changes made to these methods), then I have no issues.

Same thing just happened to my local server.
Running "Mekanism-1.7.10-8.1.1.225.jar"

Judging from the trace, there seems to be a dependency on CodeChickenCore.
My version is "CodeChickenCore-1.7.10-1.0.4.29-universal.jar"

http://pastebin.com/zERTdviM

The server seems to start just fine, but crashes when the first user tries to enter.

Updating solved this

I'm also getting this on the sever side.

I think I ran into this same Issue. Technic 1.7.10 pack, mekanism 8.1.219
http://pastebin.com/zBMSagH9

Fixed in development.

I just upgraded to .225 and still getting the same error on my upgraded server. I'll try .226... I can provide a log if needed.

Same error for .226

http://pastebin.com/09Grs5X3