Forge is not working with the new minecraft launcher. I tried downloading the 1.12.2 minecraft forge and it says "java.lang.noclassdeffounderror", then I tried opening the 1.8.9 forge, this one worked without a single problem before the new launcher, and it will just crash unexpectedly. I've been trying to fix this for about 2 hours, and I've tried to find a way to downgrade the launcher, but I can't. Please help.