Hey I'm using the latest stable version of forge for 1.12.2 and same for the mod and I'm getting an issue with the biome ID limit. There appears to be no config options for biome IDs Here's the crash report:

https://pastebin.com/rRTddNi9

It mentions DimDoors specifically which is why I made this issue. Will test to see if it's something else in the mean time.

That's because you have too many biomes, I'd suggest installing either JEID when we push our next update, or removing a mod that has any biomes. There's nothing we can do on our end besides give that advice.