Crash report(Full: https://pastebin.com/LcnM0MYE):
net.minecraftforge.fml.common.MissingModsException: Mod techguns (Techguns) requires [forge@[14.23.5.2807,)]
at net.minecraftforge.fml.common.Loader.sortModList(Loader.java:264)
at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:570)
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98)
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:333)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486)
at java.lang.Thread.run(Thread.java:745)

I know that Techguns since 1.12.2-2.0.1.2_pre3 requires latest forge (2807), recommended (2768) crashes on start.

Unfortunately, the latest version of the Sponge uses a stable version of the Forge(https://www.spongepowered.org/downloads/spongeforge/stable/1.12.2).

A Sponge is a very important modding platform without which stable_and_working chat, economy, land claims, fine tuning of rights and much more are impossible.

There is no tools to create a well-developed server on bare Forge.

So I just want to ask to add a compatibility layer for a stable Sponge(and Forge) version if possible.

In parallel, I will ask the developers of Sponge to help for their part.

Thank you for your cooperation!

We have just tested new Forge (2808) version with old Sponge (2768) and new Techguns and there is no compatibility issues at this moment. I'm sorry to trouble you.

Forge is usually compatible with mods built for older builds.