If you already know and understand SteamIDs then you will fly through this! if not then no worries I will cover how to get these and where to place them. On any Valheim dedicated server the admins live in a plain text file called adminlist.txt, one ID per line, and the same folder holds bannedlist.txt and permittedlist.txt. You can also host your own Valheim server with us and manage all three lists from the Players tab instead of touching the file.
Finding SteamIDs
You will need to find out your or the players Steam64ID which you can do so easily here on this link: https://steamid.io/
Simply enter their name in the lookup box and grab the id on the line: steamID64 e.g. 76561197967057037. Iron Gate's own documented format is Steam_ followed by that number, and the server accepts either.
If you do not know what to enter, the server log prints it when the player connects, like this:
Got connection SteamID 76561197967057037
On our panel that's the Console tab, and quicker still, once a player has connected their ID is shown on their row on the Players tab, so you can read it off there.
You can also find out in-game! If you hit F2 in the 'Players' section you will see the players name and ID.
If your server is running crossplay
Anyone joining from Xbox, Game Pass, PlayStation 5 or Switch 2 has no Steam64ID at all, so there is nothing to look up for them on steamid.io. Iron Gate gives every player a Platform User ID instead, which is the platform name, an underscore, then their ID, and it is case sensitive. You will see it in the server log when they connect (Xbox_2535416401464117 is the shape), and they can read it off the F2 panel themselves.
It goes into the same file on its own line, exactly like a Steam64ID does. Steam players are unaffected by any of this, a plain Steam64ID on its own line still works fine.
Valheim 1.0 and the new ID format
Valheim 1.0 brought in a new player ID format as well, Iron Gate's example being V_123456789, and on the 1.0.7 launch build the ban list and whitelist only recognised that new style and ignored older entries like Steam_123456789. The 1.0.12 hotfix fixed it, so both styles work again. If your bannedlist.txt or permittedlist.txt seems to be ignoring people, update the server before you start rewriting the lists.
Adding it to your adminlist.txt file
On a self-hosted server the file sits in the save directory the server was started with, next to worlds_local. Put the ID on a new line and restart:
// List admin players ID ONE per line
76561197967057037
On a LOW.MS server don't edit the file. Open the Players tab and add the ID under Admins, either by toggling Admin on a player who has already connected or with the Add by SteamID64 form underneath the roster (it takes an Xbox_ ID too). Banned and Whitelist are on the same tab. The server writes adminlist.txt from the panel's list every time it starts, so a hand edit on the Files tab (config/valheim/adminlist.txt) gets overwritten at the next start anyway.
One line worth reading twice: changes apply on the next start, not immediately. Add yourself, restart, done. You or the player will now be an admin!
And a warning on the whitelist, because it's the most expensive mistake on this page: permittedlist.txt is a whitelist, not a permissions list. Put one name in it and everyone else is locked out. If all you wanted was to make someone an admin, the admin list is the only one you touch.
Using the new found administrator powers!
To use the in game admin menu, you need to ensure you have configured the launch option in Steam!
In your steam library, right click on Valheim and select Properties
In the general tab, you will see launch options, enter -console
Then F5 in game opens the console (newer builds also have a developer console switch in the settings menu, which does the same job). To find the admin commands click on this guide here: https://low.ms/knowledgebase/valheim-admin-commands