ModlistGuard

Stops you loading a world with the wrong mods.

If you mod Valheim through r2modman or another mod manager, your mods only load when the manager launches the game. Start Valheim from Steam and you get the plain game, and the plain game deletes anything it doesn't recognise the moment it loads your world: modded buildings, crafting stations, items in chests and in your inventory. The next save makes it permanent.

ModlistGuard remembers which mods each world was last played with. If they differ when you press Start, it stops and shows you what's missing, added or updated before anything loads.

• No takes you back to the world list, and nothing is touched.
• Yes loads the world anyway, and the mods you have now become that world's mod list.

It warns about any change, not only a Steam launch: switching mod manager profiles, removing a mod, or updating one.

Installing

Installing with a mod manager is only half of it. A mod manager can only install into its own profile, and a mod there never runs when you launch from Steam, which is the launch you need protecting from. The mod manager half records your worlds' mods; the Steam half shows the warning. Do both.

1. In your mod manager

Install ModlistGuard into the profile you play with, as you would any other mod.

Then launch through the mod manager and open each world you care about once. That's how ModlistGuard learns their mods. Until a world has been opened this way, a Steam launch can only tell you it has no record of that world, not what's missing from it.

2. In your Steam Valheim folder

1. In Steam, right-click Valheim → Manage → Browse local files. This opens the Valheim folder, the one containing valheim.exe.
2. Download BepInExPack_Valheim from Thunderstore with Manual Download, and unzip it. Copy everything inside its BepInExPack_Valheim folder into the Valheim folder, replacing files if asked. Your Valheim folder should now have a BepInEx folder next to valheim.exe.
3. Inside that BepInEx folder, create a folder named plugins.
4. Download ModlistGuard with Manual Download, unzip it, and copy plugins\ModlistGuard.dll into Valheim\BepInEx\plugins\.

That's it. Launching from Steam now loads only ModlistGuard, and launching from your mod manager still loads your full profile, as before. Your mod manager points the game at its own profile when it launches, so what you put in the Valheim folder doesn't affect it.

Optional: a Steam launch will open a black log window alongside the game. To hide it, open Valheim\BepInEx\config\BepInEx.cfg, find [Logging.Console], and set Enabled = false.

Uninstalling

Delete the BepInEx folder from your Valheim folder, and remove ModlistGuard from your mod manager. Steam's Verify integrity of game files won't remove it for you.

Settings

In BepInEx\config\com.noodle.modlistguard.cfg, in each install you want them to apply to:

• IgnoreVersionChanges — only warn when a mod is added or removed, not updated.
• IgnoredMods — a comma-separated list of mod GUIDs that never count, for mods that can't affect a save, like UI or minimap tweaks. Each file in the modlist_guard folder below lists a world's mods with their GUID first.

Good to know

• Only worlds you host from the main menu are checked. Dedicated servers aren't, and joining someone else's server isn't affected.
• Mod lists are kept on this PC, in %USERPROFILE%\AppData\LocalLow\IronGate\Valheim\modlist_guard\, shared by every mod manager profile and the Steam install. On another PC, a world's mods are learned again the first time it's opened with mods.
• Back up your world before trusting any mod with it, this one included. Steam Cloud saves are in Steam\userdata\<your id>\892970\remote\.