[MC-132974] Converting 1.12 world to 1.13 spams Chunk file at x,y is missing level data, skipping

When I load a 1.12 world into 1.13, I get this error spammed.

Chunk file at x,y is missing level data, skipping

It even continues to spam it as I play the world. When I get into the world, some old chunks get replaced with new chunks.

Linked issues

When you open the previous version of the 1.13 pre release version, you must backup it, otherwise there will be bug.

I did backup the world, I created the world to demonstrate this issue. It also happens in other 1.12 worlds too.

Do you have a backup

Don’t listen to this poster ^^

I can link the world here so you can reproduce the issue.

Yes, please attach the world from 1.12.2. Also, can you attach the full launcher log?

I have seen this bug in a fresh 1.12.2 world by creating a new world in 1.12.2 and then loading it in 1.13.pre6.