The server crashes when both Quark and SpongeForge installed. fml-server-latest.log It didn't output a crash log, sorry

I'd report this to sponge.

This is the relevant transformer: https://github.com/Vazkii/Quark/blob/master/src/main/java/vazkii/quark/base/asm/ClassTransformer.java#L402-L420

Getting the same issue. It looks like Mumfrey posted a solution but needs to be fixed in Quark.

Will be fixed on the next version