17 launch arguments · 10 players · Valheim 1.0.17

Dedicated server

The server reads 17 arguments. With none it loads the world Dedicated on port 2456, public, keeping 4 auto backups and saving every 30 min. Up to 10 players.

-name "My server" -world "Dedicated" -port 2456 -password "secret1" -crossplay

Port

2456

default

Players

per server

World saves

30 min

every

Auto backups

kept

Launch arguments

Argument Default What it does

-world <name> Dedicated The world to load; the server creates it if there is no world by that name.

-name <name> the world's name The server's name in the server list.

-port <number> 2456 The port the server listens on (Steam and crossplay).

-password <text> — Required to join. A public server refuses to start unless it has at least 5 characters and isn't part of the world's name or seed.

-savedir <folder> the game's save folder Where worlds, backups and the admin, ban and permitted lists are kept.

-public 1 or 0 1 1 makes the server public; 0 doesn't. Only a public server checks the password rule.

-logfile <file> — The log file; the server notes it in the log.

-crossplay — Runs the server on the crossplay backend (PlayFab) instead of Steam; it gets a six-digit join code.

-instanceid <id> — Stored at start-up; nothing else in the game's code reads it.

-backups <number> 4 How many automatic backups to keep; 0 or 1 turns them off.

-backupshort <seconds> 7200 (2 h) How old the newest backup must be before another is made (at least 5).

-backuplong <seconds> 43200 (12 h) How old the second backup must be before the oldest is dropped; younger, and the newest is replaced instead (at least 5).

-saveinterval <seconds> 1800 (30 min) How often the world saves (at least 5).

-resetmodifiers — Clears the world's modifiers back to normal.

-preset <preset> — Applies a world modifier preset: easy, hard, hardcore, casual, hammer, immersive.

-setkey <key> — Adds a world key, e.g. nomap or playerdamage 150.

Argument	Default	What it does
`-world` <name>	Dedicated	The world to load; the server creates it if there is no world by that name.
`-name` <name>	the world's name	The server's name in the server list.
`-port` <number>	2456	The port the server listens on (Steam and crossplay).
`-password` <text>	—	Required to join. A public server refuses to start unless it has at least 5 characters and isn't part of the world's name or seed.
`-savedir` <folder>	the game's save folder	Where worlds, backups and the admin, ban and permitted lists are kept.
`-public` 1 or 0	1	1 makes the server public; 0 doesn't. Only a public server checks the password rule.
`-logfile` <file>	—	The log file; the server notes it in the log.
`-crossplay`	—	Runs the server on the crossplay backend (PlayFab) instead of Steam; it gets a six-digit join code.
`-instanceid` <id>	—	Stored at start-up; nothing else in the game's code reads it.
`-backups` <number>	4	How many automatic backups to keep; 0 or 1 turns them off.
`-backupshort` <seconds>	7200 (2 h)	How old the newest backup must be before another is made (at least 5).
`-backuplong` <seconds>	43200 (12 h)	How old the second backup must be before the oldest is dropped; younger, and the newest is replaced instead (at least 5).
`-saveinterval` <seconds>	1800 (30 min)	How often the world saves (at least 5).
`-resetmodifiers`	—	Clears the world's modifiers back to normal.
`-preset` <preset>	—	Applies a world modifier preset: easy, hard, hardcore, casual, hammer, immersive.
`-modifier` <modifier> <option>	—	Sets one modifier: combat veryeasy\|easy\|default\|hard\|veryhard; deathpenalty casual\|veryeasy\|easy\|default\|hard\|hardcore; resources muchless\|less\|default\|more\|muchmore\|most; raids none\|muchless\|less\|default\|more\|muchmore; portals casual\|default\|hard\|veryhard.
`-setkey` <key>	—	Adds a world key, e.g. `nomap` or `playerdamage 150`.

Difficulty on a server: the same presets and modifiers as the menu — world modifiers.

Admins, bans and the whitelist

Admins

adminlist.txt

Players who may run admin commands.

Banned

bannedlist.txt

Checked every 5 s; anyone on it is kicked.

Permitted

permittedlist.txt

If it lists anyone, every player not on it is kicked.

One player ID per line, in the server's save folder. For Steam players the plain Steam ID matches.

ban [name/ip/userID] - ban user

banned list banned users

kick [name/ip/userID] - kick user

optterrain optimize old terrain modifications

save force saving of world and resets world save interval

unban [ip/userID] - unban user

Console commands that work over the network without cheats. All of them: console commands.

Where worlds are saved

Save folder: %USERPROFILE%\AppData\LocalLow\IronGate\Valheim on Windows (Unity's data folder for IronGate/Valheim), or the one -savedir names.

worlds_local — worlds on this computer (worlds for Steam Cloud saves)
characters_local — characters, one .fch file each
Each world is a folder, worlds_local/<world>/, holding _main.<n> files (.fwl2, .db2, .chunks, .ok) and .chunk files; worlds saved by older versions are <world>.fwl + <world>.db

Auto backups

Backups are named <world>_backup_auto-yyyyMMdd-HHmmss. A dedicated server keeps 4 (the game itself 2). None is made in the first 20 min of a session; after that, at each save:

nothing, while the newest backup is younger than 2 h (-backupshort);
otherwise, if the second-newest is younger than 12 h (-backuplong), the newest is replaced;
otherwise a new one is added, dropping the oldest once there are 4.

So you always keep one recent backup and older ones about 12 h apart.

Questions

›What port does a Valheim dedicated server use?

2456 unless -port sets another; the server uses it for Steam and for crossplay.

›How many players can join a Valheim dedicated server?

10. The server turns the next player away as full.

›How do I make someone an admin on my Valheim server?

Put their player ID on its own line in adminlist.txt in the server's save folder (for Steam players the plain Steam ID works). bannedlist.txt bans the same way, and permittedlist.txt, if it has anyone in it, lets only those players in.

›How do I set difficulty on a dedicated server?

Start it with -preset (easy, hard, hardcore, casual, hammer, immersive) or -modifier <modifier> <option>, or type setworldpreset / setworldmodifier in the console as an admin while it runs.

›Where does a Valheim dedicated server save the world?

In worlds_local inside the save folder (%USERPROFILE%\AppData\LocalLow\IronGate\Valheim on Windows), or in the folder -savedir names.

›How often does a Valheim server make backups?

It keeps 4 automatic backups by default, none in the first 20 min of a session. A save makes one once the newest backup is 2 h old; while the second-newest is younger than 12 h it replaces the newest, otherwise it is added and the oldest dropped.

Formula

The argument list, every default and the file names are read from the game's code each patch; the server stops reading a world modifier name it can't parse and logs an error.

FejdStartup.ParseServerArguments, ZNet (player limit, admin/ban/permitted lists), SaveSystem.ConsiderBackup, Game.m_saveInterval — Valheim 1.0.17