DeepNorthTerrainFix
Heals duplicate terrain compilers that delete Deep North terraforming, trap players in portals and cause snow seams. Server + client.DeepNorthTerrainFix
Created by FlorpyDorp. MIT licensed.
Fixes the Valheim 1.0 Deep North bug where a zone's terraforming vanishes, players get stuck forever in a portal or on the login screen while someone is standing in that zone, the terrain flickers between two shapes, and hard seams appear along zone borders in the snow.
Works as a server mod (heals the world you already have and stops new damage from arriving) and as a client mod (stops the damage at the source). Install on both for full protection. One DLL for both.
What it does
Heals the save
- On world load, every 2 minutes, and whenever a new terrain compiler arrives over the network, it finds
zones that have more than one
_TerrainCompilerobject, merges their terrain data into the one with the most data, and removes the rest. The result is written with the next world save. - Console commands to scan, fix, reconcile zone-border seams, or reset one zone's terrain (buildings kept).
Prevents new damage (client side, where terrain objects actually live)
- Reuses the zone's existing compiler instead of spawning a duplicate.
- When two compilers collide, keeps the one with data instead of whichever spawned first, and removes the other properly so the create/destroy loop cannot start.
- Hard 25 s teleport timeout so nobody is trapped in a portal.
- Stops a hoe/shovel stroke that crosses a zone line from being applied twice on the shared column (the one-vertex ridge along zone borders in snow).
- Optional: raises the Steam send-rate cap and ZDO budget, and throttles the per-piece snow-buildup sync that floods the network at large bases during snowfall.
Cannot do: bring back terraforming that vanilla already deleted. For that you need a backup of the world folder from before it happened (the mod only stops it happening again).
Install
- Install BepInExPack for Valheim on the dedicated server and on every client.
- Drop
DeepNorthTerrainFix.dllintoBepInEx/plugins/. - Start the server once. The log shows
[heal on load]lines for every zone it repaired. Typesavein the server console (or wait for the autosave) to persist it.
Back up your world folder before the first run. The mod changes world data.
Who needs it. Each part of the fix runs where the problem lives:
| problem | server only | one modded client | every client |
|---|---|---|---|
| duplicate compilers deleting terraforming | healed as they arrive and on load (a one-tick race remains) | healed in that player's area | prevented at the source |
| dead stroke objects that trap players in portals | removed the moment they arrive, and on load | removed in that player's area | never created |
| portal hang escape (25 s timeout) | no | that player only | yes |
| double-applied border strokes (snow ridges) | no | that player's strokes only | yes |
| network budget / snow sync throttling | server half | that player's half | yes |
So: server alone stops the terraforming loss and the portal trap for everyone. Everyone installed is the full fix.
Console commands
Type in the dedicated server console, or in the F5 console as the host of a local game. A joined client can type the write commands too: they are forwarded to the server, which only runs them for players on its adminlist (results appear in the server console/log).
| command | what it does |
|---|---|
dntf_scan |
Lists zones with more than one terrain compiler. Read-only, local. |
dntf_zone |
Prints your current zone coordinates and its compilers. Local. |
dntf_fix [nomerge] |
Merges and removes duplicate compilers in the whole world. |
dntf_seams [heights|paint|both] [zoneX zoneY radius] |
Makes every shared border vertex agree across the zones that own it (one-sided edits are copied across, conflicting ones averaged, corners resolved once). Whole world unless a centre zone and radius are given. A host can also type dntf_seams both 3 for 3 zones around their character. |
dntf_reset <zoneX> <zoneY> |
Wipes one zone's terrain modifications. Buildings stay. Terrain returns to world generation. |
dntf_zdos <zoneX> <zoneY> [radius] |
Lists every object type in a zone as the running game sees it: prefab name, count, how many are non-persistent (never saved), owners, and on a client how many are stuck as "created but dead" (the state that blocks portals). Local, read-only. |
dntf_purge <zoneX> <zoneY> <prefab> [radius] |
Removes non-persistent objects of one prefab (name or hash from dntf_zdos) from a zone. Never touches buildings or anything that is saved. |
Zone coordinates: zone X = round(worldX / 64), zone Y = round(worldZ / 64). dntf_zone does it for you.
Config (BepInEx/config/FlorpyDorp.DeepNorthTerrainFix.cfg)
| section | key | default | notes |
|---|---|---|---|
| Heal | HealOnWorldLoad | true | server/host: dedupe whole world after load |
| Heal | HealOnArrival | true | dedupe a zone the moment a new compiler ZDO arrives |
| Heal | HealPeriodically / HealIntervalSeconds | true / 120 | server/host full scan |
| Heal | MergeDuplicateData | true | union the duplicate's vertices into the survivor before removal |
| Heal | ClientMayHeal | true | let joined clients run the arrival heal and ghost purge too |
| Heal | PurgeGhostTerrainOps | true | remove ZDOs whose prefab is a self-destructing terrain op (on load, on arrival, periodic sweep) |
| Terrain | FixDuplicateCompilers, MergeOnDedupe, ReuseExistingCompilerZdo | true | client-side prevention |
| Terrain | SkipUnownedNeighborSpread, FixDoubleAppliedBorderStrokes | true | seam prevention |
| Terrain | CleanupNetworkedTerrainOps | true | a stroke object that carries a network view is destroyed properly instead of leaving a dead ZDO that blocks "area ready" |
| Teleport | HardTimeout / HardTimeoutSeconds | true / 25 | portal hang escape |
| Network | PatchNetworkBudget, SteamSendRateBytesPerSec, ZdoInFlightBudgetBytes | true / 512000 / 30720 | vanilla 153600 / 10240 |
| Snow | ThrottleSnowWrites / SnowWriteStep | true / 0.05 | piece snow-buildup sync |
Why this happens (plain language)
Every 64 m square of the map has one invisible "terrain notebook" (the game calls it a terrain compiler). Every hoe, pickaxe and snow-shovel stroke in that square is written into it. There should be exactly one per square.
When you shovel or hoe near the edge of a square, or when someone portals in and starts working before their game has finished spawning that square's objects, the game looks for the notebook only among objects already spawned on that player's screen. It doesn't find it, so it creates a brand-new blank one. Now the square has two notebooks.
When the game later has both on screen it always destroys the one it spawned first, without looking at which one holds the real data. If the player doing this "owns" that notebook (the nearest player owns the objects around them), it is deleted from the world for everyone: all terraforming in that square snaps back to how the world generated it. If they don't own it, the game cannot delete it, so it re-spawns it next tick, which destroys the other one, and so on thirty times a second. While that loop runs the square never counts as "ready", and the portal and login screens wait for "ready" with no timeout. That's the friend stuck in the portal until the owner walks out of the square and ownership moves to them.
Snow. In the Deep North the snow depth is stored in that same notebook, as one number per metre of ground, and drawn as up to two metres of height. Each square's grid is separate; nothing blends across the line between two squares. So any time two neighbouring notebooks disagree about their shared edge you get a dead-straight step along the zone line: one notebook was deleted (above), one square got a stroke and the other didn't (dropped network message), or, a genuine code bug, a stroke that overlaps two squares is applied to both squares and copied across the border, so the shared column gets it twice. Old-style paint was a blend that barely moved when applied twice; snow paint is additive, so the second application shows as a ridge.
Why the border seams were never fixed. They were always there, just faint: each square computes its lighting from its own triangles only, and any edit that reaches one side of a line but not the other leaves a small step. Before 1.0 that was a lighting line and the occasional crack. The Deep North turned the paint layer into geometry, so an invisible paint mismatch became a wall.
Notes
- Built against Valheim 1.0.12 from decompiled code and verified against it line by line. It has not been
soak-tested on a busy public server yet; please report issues with your
BepInEx/LogOutput.log. - When the server heals a zone that a player is actively terraforming, that player's copy reloads the merged block (a brief terrain rebuild) and at most one in-flight stroke can be lost. The player keeps ownership of the zone throughout.
- Snow-buildup throttling keeps the accumulated value locally between syncs, so snow still piles up and heavy-snow damage still triggers; only the network traffic is reduced.
- Source, the full bug analysis and a Python tool for offline save repair: see the repository.
- Author: FlorpyDorp. Bug reports and feedback are welcome on the Thunderstore page or the repository.