Valheim Mods Broken After 1.0.21? MissingMethodException Fix

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Valheim 1.0.21 changed four game methods mods call, so older builds throw MissingMethodException. Find the mod in LogOutput.log and fix your server in order.

Valheim logo above two Vikings resting at a campfire in a dark forest

Since Valheim patch 1.0.21 came out on 28 October 2026, some modded servers act strange. Cooking stations stop cooking, a mod's window shows placeholder text, or a mod switches itself off at startup, while everyone can still join. The BepInEx log fills up with lines such as MissingMethodException: Method not found. This guide shows what 1.0.21 changed for mods, how to find the broken one in BepInEx's LogOutput.log, and the order to fix it in on a dedicated server.

Quick answer: When your Valheim mods are broken after update 1.0.21, the cause is usually a mod build made for 1.0.20. The patch changed the parameters of CookingStation.SetSlot, PlayerProfile.GetStat and two ship sail methods, so an older mod that calls one of them throws MissingMethodException (or a related reflection error) and its feature stops working. Open BepInEx/LogOutput.log on the server and on one player's PC, read the line under the exception to get the mod's name, and update that mod. If there is no fixed version yet, disable it on the server and on every client, and keep the mod versions the same everywhere.

What Valheim 1.0.21 Changed for Mods

The 1.0.21 patch notes list bug fixes and tweaks, such as Kall Fimbulbringer's drops no longer falling through the floor and three foods moving from the Cauldron to the Food Preparation table. Nothing about mods. Iron Gate has no official mod support, and its Regarding Mods post says it "can't guarantee that mods will be compatible with newer versions of the game".

Steam's app info (api.steamcmd.net) shows the dedicated server, app 896660, on public build 26266951 since 28 October, 13:16 UTC.

Mod authors who compared the game code of 1.0.20 and 1.0.21 (assembly_valheim.dll) found changed signatures in four methods. They are listed in a decompile diff in the lembitu server repository and confirmed by the mods that broke:

Game method1.0.201.0.21
CookingStation.SetSlot(int, string, float, Status, bool)Adds a sixth parameter, long sender = 0
PlayerProfile.GetStat(PlayerStatType)(PlayerStatType, DifficultyRequirement); the old version is gone
Ship.UpdateSail, Ship.UpdateSailSize(float)Add bool haveControllingPlayer

Why an optional parameter still breaks a mod. A compiled mod calls a game method by its exact signature, and default values are filled in at compile time. A DLL built against 1.0.20 still asks for the five-parameter SetSlot, which 1.0.21 no longer has, so the runtime throws "Method not found". The GrindstoneSkills report notes that rebuilding against the 1.0.21 game files is enough, without code changes. No config setting fixes it; a new build of the mod does.

Why everyone can still join. The same diff shows the network version at 41 in both builds, so 1.0.20 and 1.0.21 can connect to each other and the breakage only shows up as features that stop working. That will change: the patch notes hold back part of a Frost Foundry fix because it "requires network incompatible update and is coming soon". If players get refused instead, our incompatible version guide covers that error.

The Errors Mod Authors Reported After 1.0.21

The bug reports from 28 October onward show three kinds of error.

1. A direct call to the old method. GrindstoneSkills 0.20.3 logged this on every client that owned a cooking station:

[Error  : Unity Log] MissingMethodException: Method not found: void .CookingStation.SetSlot(int,string,single,CookingStation/Status,bool)
Stack trace:
GrindstoneSkills.StationPerks.Prefix (CookingStation __instance, System.Collections.Generic.List`1[GrindstoneSkills.StationPerks+Shift]& __state)
(wrapper dynamic-method) CookingStation.DMD<CookingStation::UpdateCooking>(CookingStation)

single is .NET's name for float. The error came from a patch that runs before the game's own cooking update, so that update was cut off too and cooking stations and ovens stopped cooking. RestlessCook's Cookbook logged the same exception and stopped cooking. Odin's Hearth logged Method not found: single .PlayerProfile.GetStat(PlayerStatType) every frame, and its window showed only dummy text.

2. A lookup that fails at startup. RunicProduction 2.3.4 searches for the method by its parameter list, finds nothing and switches its automation off:

[Warning:  HarmonyX] AccessTools.Method: Could not find method for type CookingStation and name SetSlot and parameters (int, string, float, CookingStation+Status, bool)
[Error  :Runic Production] Runic Production disabled its automation; vanilla production remains active. startup validation failed TypeInitializationException: The type initializer for 'RunicProduction.Integration.ValheimAccess' threw an exception.

3. A reflection call with the wrong number of arguments. StoreAndCraft 1.6.2 passed five values to the six-parameter method:

[Error  : Unity Log] TargetParameterCountException: Number of parameters specified does not match the expected number.

The stack trace under it names StoreAndCraft.CookingAutoDrop.TryDepositDoneToChest. This one had a side effect: the cooked item was already in the chest when the call failed and the slot was never cleared, so cooked food could be duplicated into chests. If you ran that version on 1.0.21, check the chests next to your cooking stations.

Not every red line after a patch comes from the patch. Zen.ModLib logs VERSION MISMATCH on 1.0.21, but the lembitu decompile shows the check only writes to the log. And a ValheimOne startup error on 1.0.21 (Failed to patch void ZNet::RPC_PeerInfo) is one its maintainer reproduced when a second mod also changes the 10-player limit: two mods clashing, which the next ValheimOne release should turn into a warning.

Find the Broken Mod in BepInEx's LogOutput.log

BepInEx writes its log to BepInEx/LogOutput.log in the folder the game or server runs from (source). The BepInExPack Valheim config sets WriteUnityLog = true, so the game's own errors, the [Error : Unity Log] lines above, land in the same file. It also sets AppendLog = false, which means the file is overwritten every time the game or server starts. Copy the log before you restart.

Where to find it:

  • Dedicated server: BepInEx/LogOutput.log inside the server folder, next to valheim_server.x86_64 on Linux or valheim_server.exe on Windows.
  • Players using r2modman: BepInEx/LogOutput.log inside the profile folder, which is where r2modman looks for it. Its settings also have Copy log to clipboard, which copies the log's contents formatted for Discord.
  • Manual install on Windows: steamapps\common\Valheim\BepInEx\LogOutput.log in your Steam library.

Work through it in four steps. The commands assume the server folder from our Valheim dedicated server guide, /home/valheim/server.

Confirm the build. The pack's own build of BepInEx (source) prints the game version near the top, in a line like [Message: BepInEx] Valheim Version: l-1.0.21 (from a public 1.0.21 server log).

List the errors, most frequent first. BepInEx lines have no timestamps, so identical errors collapse into one line with a count:

cd /home/valheim/server
grep -E "MissingMethodException|TargetParameterCountException|Could not find method|Failed to patch" BepInEx/LogOutput.log | sort | uniq -c | sort -rn

Read the lines under each exception:

grep -A 6 -E "MissingMethodException|TargetParameterCountException" BepInEx/LogOutput.log | head -n 40

Under Stack trace:, skip lines that start with System. or (wrapper (in StoreAndCraft's report, three System.Reflection lines came before the mod's own line, which is why the command shows six lines). The first line left names the mod's code: GrindstoneSkills.StationPerks.Prefix means GrindstoneSkills, RestlessCook.KitchenRun.Tick means RestlessCook. For lookup warnings, the line after the warning often carries the mod's name in its bracket, as in [Error :Runic Production].

Match the name to a DLL and a version:

grep "Loading \[" BepInEx/LogOutput.log
grep -rl --include="*.dll" "GrindstoneSkills" BepInEx/plugins

The first command lists every plugin BepInEx loaded: the pack's BepInEx logs each one as Loading [name version] (GUID), for example Loading [GrindstoneSkills 0.20.3] followed by the mod's ID. Save that list from the server and from a player's log: it's the quickest way to compare versions. The second command finds the DLL that contains the name you read in the stack trace.

On Windows, run this in PowerShell from the folder that holds BepInEx:

Select-String -Path .\BepInEx\LogOutput.log -Pattern "MissingMethodException","TargetParameterCountException","Could not find method","Failed to patch" -Context 0,6 | Select-Object -First 10

Check the server log and a player's log. Code that only runs on a player's PC never logs its error on the server: the lembitu server loaded AzuExtendedPlayerInventory 2.6.3 without errors, while the author's 2.6.5 notes say its stats panel was erroring on 1.0.21.

Fix It in This Order on a Dedicated Server

  1. Stop the server and back up. Copy the world, BepInEx/config and the Loading [ list from the log, so you know which versions worked. Our backup restore guide shows where Valheim keeps its worlds. On our Valheim server hosting the server files update automatically when Iron Gate ships a patch, so check your mods on patch day; every plan has 2 or 3 backup slots in the control panel for a copy before you change anything.
  2. Update the mods the log names. Check the author's own page as well as your mod manager. On 3 November, the 1.0.21 fix for AzuExtendedPlayerInventory (2.6.5, 30 October) was on Hexium, while Thunderstore still listed 2.4.14 from 14 September. A manager that only reads Thunderstore says that mod is up to date when it isn't.
  3. Leave BepInEx alone unless a mod asks for a newer one. BepInExPack Valheim 5.4.2360 came out on 28 October, but its changelog is about BepInEx 5.4.23.6 and Doorstop and doesn't mention 1.0.21. The lembitu server booted 1.0.21 on the older 5.4.2351 with 68 plugins loaded and none failed. A MissingMethodException from a mod is fixed in the mod.
  4. No fix yet? Disable the mod everywhere it runs. Turn it off in the mod manager, or move its folder out of BepInEx/plugins: BepInEx loads every .dll in that folder and its subfolders (TypeLoader), so a moved file is not loaded. If the mod runs on both sides, players turn it off too. Before you remove a mod that adds items, building pieces or creatures, read what its page says happens to that content, and keep the backup from step 1.
  5. Give everyone the same versions. Mods built on Jotunn can disconnect a player whose version doesn't meet the mod's rule, and ServerSync disconnects a client older than the minimum version a mod sets. Share one profile code with your group, as in our Thunderstore mods guide.
  6. Start, check and test. Look for the Chainloader startup complete line in the new log, which the pack ends with counts such as (68 loaded, 1 skipped, 0 failed), run the grep from above again, then try the feature that broke: cook something, open the mod's window, take the helm.

Mods With Known 1.0.21 Breaks (3 November 2026)

ModWhat broke on 1.0.21Fixed in
GrindstoneSkills 0.20.3SetSlot missing; cooking stations and ovens stop cooking0.20.4, 28 October
StoreAndCraft 1.6.2Cooking auto-store throws TargetParameterCountException; cooked food can be duplicated1.6.3, 29 October
Station Item Return 1.0.0Returning an uncooked item can fail with a missing-method error1.0.1, 29 October
Odin's Hearth 0.1.5GetStat missing; the window shows dummy text0.1.6, 30 October
AzuExtendedPlayerInventory before 2.6.5Stats panel errors2.6.5, 30 October (Hexium)
RestlessCook (RestlessValheim)SetSlot missing; the Cookbook stops cooking0.5.5, 2 November
RunicProduction 2.3.4SetSlot lookup fails; the mod switches its automation offNo fix yet; report still open

Mods that call the sail methods directly, or look them up by their old parameter list, need a rebuild for the new UpdateSail parameter too; SailTrim's fix was still unmerged on 3 November.

FAQ

Why are my Valheim mods broken after the 1.0.21 update? Patch 1.0.21 changed the parameters of CookingStation.SetSlot, PlayerProfile.GetStat and two ship methods. A mod compiled against 1.0.20 that uses one of them still asks for the old version, so the call fails. Update to a build the author released after 28 October.

What does "MissingMethodException: Method not found" mean in Valheim? A mod asked for a game method with a signature that no longer exists. The text after "Method not found" is the old signature, and the first non-system line of the stack trace below it names the mod.

Where is the BepInEx log file in Valheim? BepInEx/LogOutput.log in the game or server folder, or in your r2modman profile folder. It is overwritten every start, so copy it before you restart.

Can I roll Valheim back to 1.0.20 until my mods are updated? Steam's app info lists a default_old branch, "Previous stable", for the game and the dedicated server; on 3 November the server's branch held build 25909431, which the lembitu repository identifies as 1.0.20. The same repository reports that Steam refused that build to an anonymous login, the login SteamCMD normally uses for a dedicated server. The server and every player would have to switch, and we found no Iron Gate page about it. One RunicProduction user kept their server on 1.0.20 instead, which only works while the network version matches and doesn't help client-side mods. The next network-incompatible patch ends both options, so update or disable the mod.

My mod manager says every mod is up to date. Why do I still get errors? Some authors publish fixes outside Thunderstore first. AzuExtendedPlayerInventory's 1.0.21 fix was on Hexium while Thunderstore still had a September version. Check the version in the Loading [ line against the author's own page.

Do the server and the players need the same mod versions? For any mod that runs on both sides, yes. Mods built on Jotunn or ServerSync can check versions when a player joins and disconnect a mismatch, and a fixed server with an old client still breaks for that player.

Sources

All opened on 3 November 2026: