Whenever I use the /feiop command in single player, my game crashes shortly afterwards. The crash usually results within 5 - 15 seconds of the command, but has taken close to 45 seconds to a minute on occasion. My crash report mentions an OpenGL error, but I don't know why this command would interfere with OpenGL. Additionally, my graphics drivers are all up to date.

Crash report: http://pastebin.com/a9K41iXH
Latest.log: http://pastebin.com/eHhB57Kg

Any help would be greatly appreciated.

Actually, this has nothing to do with GL.

java.lang.AbstractMethodError

Just noticed: you're using 1.9.4 versions for mc 1.9. Either download 1.9 excore & FEI versions or update forge to 1.9.4.

Thanks for the reply. I had tried running with forge 1.9.4 before, but was getting a crash on startup. I just updated again though, and it seems the problem was with an incompatible version of Optifine rather than with your mod. Thanks for the help, love your mod.

Nice. So is everything working now?

Yep. Updated Optifine, and everything's running smoothly.

Ok. Good to know.