Hello,

I have a server on 1.11.2 with running buildcraft 7.99.8.1. Every time I join the server, it says me that this version is in Alpha. I didnt find any newer version for 1.11.2 so is there any possibility to hide this "update message" for me and other players when joining?

That's a good point, BuildCraft for 1.11.2 is basically not receiving updates anymore so the warning message is slightly less useful than for 1.12.2.

(Just FYI 7.99.8.2 has been released here: https://mod-buildcraft.com/pages/download.html)