Crashing when joining server

[Jlw111]

/viaversion dump Output

https://dump.viaversion.com/83fe11e6c5079bbe04c99f6b139703bb4f4187d0526bc2f511737fb9649e3db7

Console Error

https://mclo.gs/yQwPhLX

Bug Description

Crashes whenever I attempt to join my 1.21.4 Paper server using 1.7.2 client.
My player was riding a minecart on the roof of the Nether when I last logged out.

Steps to Reproduce

1. Create 1.21.4 Paper server
2. Login with 1.21.4 client, place minecart track on the Nether roof, and start riding the rails
3. Log off, and then log back on with 1.7.2 client
4. Immediate crash

Expected Behavior

Player should be able to continue riding the rails, and not be disconnected from the server

Additional Server Info

No proxy. Self hosted server, joining through localhost. Latest development version of Paper. Completely vanilla 1.7.2 client.

Checklist

• Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. Velocity), 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

[Barvalg]

[TCAtrevor]

I'm having this issue as well on my ViaProxy instance, it just occurs when you are trying to ride any entity.

[threshold9394]

This is an issue I reported, long usernames corrupt ViaRewind servers, but this error is different, try to update ViaRewind, ViaVersion, And ViaBackWards, also install VIaRewind Legacy Support. If this still persists, update minecraft too.