Valheim mods after 1.0: what broke and what to do

Why every Valheim mod stops working at 1.0, the order to put them back in, how to read the failure in the log, and the crossplay claim that is wrong.

Nothing you have installed will work on 9 September. That is not a warning about risk, it is the expected outcome, and planning around it is easier than reacting to it.

#Why all of it goes at once

A plugin is compiled against a particular build of the game and patches specific methods inside it. Change those methods and the patch no longer finds what it is aiming at. A biome release changes a great many of them.

Iron Gate's position is published and unambiguous: "Since we don't have any official mod support, we cannot guarantee that any mods will be functional when 1.0 releases." There is also no public test branch carrying the Deep North, so no author has had an early build to compile against. Everyone gets the release at the same moment, and the work starts then.

The engine is not the problem this time. Valheim moved to Unity 6 back in February's anniversary patch, and whatever that broke was broken in February.

#The order to do this in

1. Back up, and check the backup is listed.
2. Remove every plugin before you update. On Hostd that is the Mods tab, uninstall, which clears them from the next boot. Elsewhere, empty BepInEx/plugins.
3. Update to vanilla 1.0 and start the server. Confirm it boots clean and someone can join.
4. Leave it alone for a few days. Let the world convert, let your group play, let mod authors ship.
5. Add plugins back in small batches, restarting between each. Two or three at a time makes the offender obvious when one of them is not ready.

Skipping step 3 is how a mod failure and a save conversion problem arrive together and become impossible to tell apart. Iron Gate note the new save system has not been tested with mods, which is reason enough to convert the world clean.

On Hostd the loader itself is not your problem: BepInEx is part of the image and gets overlaid on every boot, so there is no separate mod loader to update. On a self-hosted box, update BepInEx before anything else.

#Reading the failure

BepInEx is loud when a plugin fails, and the useful lines are near the top of the server console after a restart.

• Loaded N plugins tells you how many made it. Compare it with how many you installed.
• A plugin that throws during load names itself in the first or second red line. That is the one to remove.
• MissingMethodException, TypeLoadException or a Harmony patch failure all mean the same thing in this context: the plugin is built for the old version.
• A client that connects and immediately drops usually means a mod mismatch, not a server fault. Server and clients need the same list.

Work top down. One failing plugin often takes others with it, so the second error is frequently a symptom of the first.

#Server-side or client-side

Most Valheim mods need installing on every player's machine as well as the server. That doubles the update problem: a plugin is only usable again when your group can install the same version, and the slowest person in the group sets the pace.

Server-side-only mods are the minority and they are the ones to bring back first, because they need nothing from your players.

#Crossplay does not disable mods

A claim doing the rounds says crossplay and mods cannot coexist, on the grounds that BepInEx cannot hook the PlayFab networking path. It is wrong. Doorstop injects BepInEx when the process starts, before the server has read its command line, so plugins load whichever backend you selected.

What does break is narrower and more specific. A mod written on the assumption that every player is on Steam misbehaves once someone joins from PlayStation, and anything keyed to a SteamID64 is the usual offender. Console players also cannot install client-side files, so any mod requiring a matching client shuts them out no matter how the server is configured.

If your group is mixed, keep the list to server-side plugins and test with a console player before promising anyone anything.

#Next steps

• Installing Valheim mods with BepInEx and Thunderstore
• Updating your Valheim server to 1.0
• Valheim 1.0 and the Deep North: what it does to your server
• Valheim server troubleshooting

Written and maintained by the Hostd engineering team. Last updated 2026-09-04. Notice a mistake? Tell us.