Yup, I was trying to set it to at least 300. Oh well, I guess I won't be able to build on the nether roof 
Posts by Inedial
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My server is running on 1.18.1 (39.1.2) Forge, whenever I try changing the max-build-height setting to anything besides 256 it gives me a red X.
I'm also using Terralith if that changes anything.