Valheim
Valheim Dedicated Server
A Password Is Mandatory
Valheim refuses to start without a server password of at least 5 characters, whether the server is public or not. There is no way to run a passwordless server without mods. The password must also not appear inside the Server Name or the World Name.
Break either rule and the game logs Error bad password, fails to build the world, and exits with code 0 — which the panel reports as a crash with no obvious cause. The template checks both before launch and tells you which one failed.
Allocate Two Consecutive Game Ports
Valheim opens a second UDP socket on Game Port + 1 for the Steam query. It is hardcoded and no launch flag can move it. Without an allocation for that exact port the server never answers the browser and stays invisible, even though direct connect keeps working.
Pick a Game Port whose next port is free and add both allocations. Example: 2456 + 2457. The Query Port variable exists only so the panel opens the port on the firewall — Valheim never reads it.
Crossplay Replaces Steam Networking
Crossplay is not additive. Enabling it switches the backend from Steam to PlayFab, and players reach the server through a join code printed in the console. Disable it to use the Steam backend and the Steam server browser.
No Server Console
Valheim exposes neither RCON nor a stdin console, so the panel console is read-only. Admin commands run in game: put platform IDs (Steam_7656…, one per line) in saves/adminlist.txt, restart the server, then press F5 in game.
Dedicated servers accept only the admin commands — kick, ban, unban, banned, save, ping, info. Cheat commands such as spawn, god and fly are refused regardless of admin status.
Worlds and Player Lists
Worlds are stored in saves/worlds_local. The adminlist.txt, bannedlist.txt and permittedlist.txt files sit in saves/ and are editable from the file manager. A non-empty permittedlist.txt puts the server in whitelist mode: only the listed IDs can connect.
Backups
Valheim's own rolling backups are disabled in favour of the panel's Backups. The Save Interval setting is not a backup — it is the autosave of the live world, and it decides how much progress is lost if the server crashes.
World Modifiers
Presets and modifiers (combat, death penalty, resources, raids, portals) only take effect when a world is first created, so they are not exposed in the panel. Change them from the in-game console as an admin.
Official Documentation