Blocks are swapped for players on Create Flavored Forge server

[logFerF]

I recently set up an old computer as a minecraft server. Players are able to join and interact with the world just fine, except many blocks are swapped with unrelated modded and vanilla blocks. (e.g. netherrack -> waterlogged open trapdoor)

When these blocks are broken, they will only drop into an item if you switch to the tool that would break it if the block was "correct." The item that drops is the block that should be there, and when it is placed back down it immediately becomes the same wrong block again. Some chunks wont load at all and it is generally very laggy on the client side. This leads me to believe that it's an issue with the server.

The server is running 1.19.2 Create Flavored (SERVER) on a Mac Mini (Linux Mint Cinnamon) and the client is running the client side version. Connectivity is good and there are no resource issues on the server side.

Getting a friend to join results in identical block swapping. Restarting the server does not change anything, nor does restarting the computer. Adding or removing mods either crashes the server, prevents players from joining, or results in no change. Loading the world in singleplayer fixes the issue, but now only one person can play.

I have worked with my friends for several days now trying to find any solution to this problem. Most things either do nothing or crash the server. If anyone could help or has had a similar experience, please share.

Below are some screenshots:

[warjort]

When minecraft stores a chunk (section) it uses a pallette, something like

0=Air,1=Stone,2=Netherrack followed by an array of those numbers to describe the chunk section 0,1,1,1,42, etc.

If you are seeing block swapping then it sounds like this palette is corrupted for that chunk section.

It uses the same technique when sending chunks over the network.

 

You can test if it is a problem with the files themselves by taking the save and loading it into a single player. If that works then something is breaking the networking/client code.

Either way, the likely problem (beyond broken disk hardware) is one of your mods. If it is not just totally broken, it might be for a different version of minecraft which is why it breaks things.

Also check your mods for ones that claim to optimise things, especially if they say it changes chunk loading and test a new world/save without each of them.

Repeating this process for your mods is likely the only way you will find the problem one.

 

You won't be able to remove mods that modify the worldgen from your existing save. Minecraft won't let you load a world if classes that modify its worldgen are missing.

That is why you need a new save to test and client and server must match in their mod list.

Edited May 4, 2023 by warjort

[logFerF]

14 hours ago, warjort said:

You can test if it is a problem with the files themselves by taking the save and loading it into a single player. If that works then something is breaking the networking/client code.

Either way, the likely problem (beyond broken disk hardware) is one of your mods. If it is not just totally broken, it might be for a different version of minecraft which is why it breaks things.

Also check your mods for ones that claim to optimise things, especially if they say it changes chunk loading and test a new world/save without each of them.

Repeating this process for your mods is likely the only way you will find the problem one.

I have confirmed the version of minecraft is matching, and I have also loaded the world into singleplayer (which loaded just fine, the bug was gone). I would try to remove some of the optimization mods from the server, but I already tried running it on just the client side pack which didn't crash but still was broken. I'll try to reinstall the server itself and see if that works. Thanks!

[warjort]

If it works in single player, then the problem is likely in the networking code of one of your mods.

[logFerF]

The confusing part is that the exact same mods worked fine on an Aternos hosted server, but when migrating to a private server it breaks. The world file itself is fine and technically playable but the blocks are swapped around client side. The mods' networking code should be working, but it's not.

Here's the log: https://mclo.gs/YbC4eq7

[warjort]

That's the server. If it shows any error, it will likely be on the client.