/mv version -p output

https://paste.gg/p/anonymous/8ff149fd62f54269b14bf6c5ef0be4c2

Server logs

https://paste.gg/p/anonymous/e6f7b57204b44180a8dbd3b74c850aaa

Server Version

Checking version, please wait...
This server is running Paper version 1.21-119-master@100d75a (2024-07-29T16:00:13Z) (Implementing API version 1.21-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21-113-f82bea6 (MC: 1.21)

Bug Description

Error occurs when players teleport.

Steps to reproduce

See Bug Description

Agreements

• I have searched for and ensured there isn't already an open or resolved issue(s) regarding this.
• I was able to reproduce my issue on a freshly setup and up-to-date server with the latest version of Multiverse plugins with no other plugins and with no kinds of other server or client mods.

Would need to see more of the logs, and not just a snippet. What command/method is used to change worlds? Does it happen with everyone, or just certain players? Also might be a good idea to change to Paper....https://papermc.io/software/paper

As you can already see, I use Paper. Therefore, this is no longer necessary. In addition, only one command was entered to change the world. /mvtp . Nothing more.

The error occurs regardless of which player enters the command.

We'll need more detailed reproduction instructions than that. Just using /mvtp world_2 perfectly fine for me in 1.21 paper with only MV plugins installed. Ensure your instructions are clear and tested.

The PaperMC github has an open issue for this bug too (however it seems they think the plugins need to be updated):
PaperMC/Paper#11137

I've run into the same issue myself when I have PaperMC 1.21 with both Multiverse and Worldguard.

Just PaperMC + Multiverse has no issues for me. It's when I have WorldGuard installed too that I get non-stop NPE's. PaperMC + WorldGuard and no Multiverse has no issues. As someone mentioned in the PaperMC issue, there might be some sort of issue with the combination of the three.