ViaBackwards causes time-outs in Fabric 1.20.2 - latest servers

[Kichura]

/viaversion dump Output

https://dump.viaversion.com/bf86c400d761b8d8041de9626655630294c68b1856a268346cdcde5a71eaa6ed

Console Error

The console logs can be found here.

Bug Description

When attempting to the fabric server which is 1.20.2 - latest, connections from 1.8 - 1.19 will drop with a timeout.

Steps to Reproduce

1. Install latest viafabric with latest viabackwards and viarewind,
2. Start up a clean 1.19 or older client,
3. Connect to the server,
4. Eventually timeout from the server entirely.

Expected Behavior

1.19 and older clients can join the fabric server without any issues.

Additional Server Info

1. This server does not use any proxies,
2. Fabric 0.15.0 with 1.20.4 as Minecraft version,
3. Fabric API with the three via* mods.

Checklist

• Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. BungeeCord), not on both.
• I have included a ViaVersion dump.
• If applicable, I have included a paste (not a screenshot) of the error.
• I have tried the latest build(s) from https://ci.viaversion.com/ and the issue still persists.
• I have looked at https://www.spigotmc.org/resources/viarewind-legacy-support.52924/ and it does not offer a fix for my problem

[FlorianMichael]

What happens when you use a 1.9.x client instead?

[Kichura]

What happens when you use a 1.9.x client instead?

seems to persist all the way up to 1.19 for some reason; but 1.19.1 and later is where it works fine, guess this can be moved to viabackwards github issues thread then (with title change) although i wonder if it's caused by the chat reporting system failing or something else?

[HowardZHY]

Can confirm that this also happens with 1.19.0- with 1.20.2+ NeoForge servers (without mods) using ViaProxy, but doesn't happen with 1.20.2+ LexForge servers.

[ly-nxs]

It happens to me on 1.19.4 connecting to 1.20.4

[Fauli1221]

just ran into it as well

client 1.12.2 with ornithe so that I can fix problems with wayland
server 1.20.1 fabric
ViaFabric 0.4.13+64
ViaBackwards 4.9.2
ViaRewind 3.0.6

no usefull information in server log

[Matthew-MBG]

So basically ViaFabric isn't ViaBackwardsing? lol

[Clumsius]

Has there been any way of bypassing this bug even with both ViaBackwards and Fabric API?

[Clumsius]

Still happens in latest version.

[virtualspan]

Just to add on to this, I had the same error with a Velocity proxy (version 3.3.0 snapshot 396), the only plugins were ViaVersion and ViaBackwards, with the backend server being 1.20.4 Fabric (Fabric version 0.15.11) using the FabricProxy-Lite mod (version 2.7.0) for it to work (Note: I changed the hackEarlySend option to true in it's config). Tested with ViaVersion and ViaBackwards with the latest release, 4.10.2 and the latest snapshot, 5.0.0-SNAPSHOT+399 for ViaVersion, and 5.0.0-SNAPSHOT+241 for ViaBackwards. The error only occurred with versions lower than the backend server (1.20.4) including 1.20-1.20.3, not just 1.19 and below. Also the Fabric backend server does not have ViaFabric, ViaVersion, ViaBackwards, ViaRewind or any related stuff.

UPDATE: I have since eliminated the Velocity Proxy and therefore FabricProxy-Lite due to not needing it and have tested with the latest snapshots ViaVersion: 5.0.0-SNAPSHOT+408 ViaBackwards: 5.0.0-SNAPSHOT+246 ViaRewind: 4.0.0-SNAPSHOT+164 ViaFabric (dev and main versions both tested): ViaFabric 0.4.14+72-dev, ViaFabric 0.4.14+70-main (which crashed the server) and also the latest releases being 4.10.2 for ViaVersion and ViaBackwards, ViaFabric 0.4.14+66-main for ViaFabric and 3.1.2 for ViaRewind (ViaRewind was added to the tests but its client versions were not tested). Using these I had the same exact issues as except now it was just 1.19 and below like the GitHub Issue. Also all the server details (apart from Via-stuff and the ones already mentioned are the same).

[unix-supremacist]

any news? has anyone looked at this? most of my server network is fabric, i've also had this issue, and downgrading the servers isn't really an option, so i'm wondering what can be done here other than just removing viabackwards and stopping support for older clients

[unix-supremacist]

i've did some trial and error, and it seems for fabric it's specifically the fabric networking api module that causes the issue, i haven't been able to narrow down the cause any further, i'll probably see about setting up a fabric api dev enviroment with viaversion and seeing what exactly causes the issue at some point.

[isjerryxiao]

This issue has long been reported in #658.
You may consider applying this patch https://git.jerryxiao.com/mc/ViaBackwards/commit/f800e80d99a73f935cbe7a0c1e95e14f875773e4.patch

[Kichura]

This issue has long been reported in #658. You may consider applying this patch https://git.jerryxiao.com/mc/ViaBackwards/commit/f800e80d99a73f935cbe7a0c1e95e14f875773e4.patch

This PR was closed prior, therefore this needs verification to see if it properly works or not. therefore i will keep this open in case of any relevant updates.

[FlorianMichael]

@isjerryxiao I was able to reproduce the issue now. Are you sure the patch still works? I applied it and have the same error.

[Sapodly]

not just 1.20.2,farbic 1.21 sever with viaversion and viabackwards still happen with before1.19 client😥