Version

1.20.1-FORGE

Supplementaries Version

Minecraft Forge 47.2.0 - 1.20.1

Moonlight Lib Version

monnlight-1.20.1-2.11.9

Issue Detail

Problem description
Crash when joining a server

How to reproduce

• Install Minecraft 1.20.1 and Forge 47.2.0 (this is the recommended version by Forge)
• Install Supplementaries and MoonlightLib
• Launch the game and join a server
• Game crash

How to fix the problem temporarily

• Install the first version of the mod 1.20.1Forge and install the MoonlightLib 2.7.2 version

Is the server using mods & plugins toghether?

服务器是否使用mods和plugins？

No, it also crashes on the vanilla server.

that can only ever happen in 3 ways

• server doesnt have the same mods (and its likely a vanilla server)
• client doesnt have the same mods (and its likely a vanilla client)
• some server level mod that messed up datapack registries. last known one was velocity

none of them are an issue of my mods.

Is there a way I can make so the mod works on vanilla servers?

absolutely not. You cant use a mod that adds new content to a vanilla server. Mods has new blocks, connects to the sever and server looks at its registries and goes like "what blocks?"

Infact whats even the point of using a mod that adds new content on a vanilla server. even if it could work (and it cant) you wont be able to use any of its content as server doesnt know what it is and there would be amillion of inconsnstent behaviors for the content that is modified leading to glitches of any kind

For some reason, version 1.19.4Forge of this mod loads Spigot and Vanilla server-side worlds just fine.

Fabric 1.20.1 also works fine

Fabric1.20.1 and Forge1.19.4 works fine. Why Forge1.20.1 CRASHES？

Infact whats even the point of using a mod that adds new content on a vanilla server. even if it could work (and it cant) you wont be able to use any of its content as server doesnt know what it is and there would be amillion of inconsnstent behaviors for the content that is modified leading to glitches of any kind

I updated from 1.19.4Forge to 1.20.1 and I urgently need to fix this (at least on my client). None of the other mods had this crash, even if they added new blocks.

likely because none of them added a datapack registry. Something that mods can totally do. I dont know why you would ever need this mod on a vanilla server, you wouldnt be able to use any of its content anyways. Needless to say this is not something thats is supported

He's probably making a bungee with a main vanilla lobby , and then a sub-server for modded

As long as the mod is installed, multiplayer cannot be played (most servers do not install mods), and the client should support both single-player and multiplayer, and this is where the problem arises.

If I were a developer, I would want to disable the mod feature when joining a server, I'm not sure if that would be possible. However, mods that add new blocks to the server do exist. Maybe this mod uses the datapack registry for some functionality? Anyway, I haven't had much exposure to Minecraft modding development.

Yes, it does add datapack stuff, which cannot be removed and will probably make your game crash anyway later

Maybe I should file an "enhancement" issue instead of a "bug"?

Still, I'm with @MehVahdJukaar . Why do you need the server without the mod? What's the point of it

I would like a mod client to be able to use both single-player and multiplayer.
There is no need to swap clients around.

The mod Will work in single player. As for the server, as soon as the mod is installed on server, it's supposed to work.

BUT I CAN'T CONTROL ALL THE SERVERS.

But you're not supposed to join them with the mod installed? Really I don't get your complaining. If you got a problem, fork the repository, remove the error thrown and just run the game. But do not come here if your game completely breaks after that

Mods are not supposed to be used on a vanilla server. Some might work? Yes, but others don't. Just like this one.

I don't understand why 1.19.4Forge can join vanilla servers, but 1.20.1Forge cannot. That's my only doubt.I try to find help

Definitely something has been changed, but only med knows if it was mandatory to make that change. As said before the error can be removed but i have no idea what would happen. What I recommend to @MehVahdJukaar is to make the client refuse to join the server, instead of crashing the game

obviously you cant play multiplayer with a server that has a different mod set than the one you have. If you want to play vanilla just boot up a vanilla instance. is ats simple as that. If you try to log into a forge server with create and you dont have create it wont even let you in.

theres no way to "disable the mod features". Registries and mods are setup early when the game boots. If all registry content was datapack registries it could be done one day but we are nowhere near that

Fine,thx.

I tried making a mod to ignore the datapack check, as i needed it
https://github.com/LIUKRAST/DatapackIgnore/releases/tag/release