June 20, 2022 (2) Patch
From Valheim Wiki
Source: Patch 0.209.9
Dedicated-server world loading fix.
This patch fixes the world load issue introduced in 0.209.8, causing dedicated servers to fail to load worlds saved in the now legacy “worlds/” directory (and instead creating a new empty world)
Unfortunately if you already got a world-reset caused by this, try removing the broken world from "worlds_local/" (but don’t touch “worlds/” ). This will make the server load the original working world from “worlds/” instead.
We're really sorry about this, thank you for being understanding!