Valheim World Modifiers on a Dedicated Server: Every Preset, Modifier and Key

You set portals to casual, changed your mind, deleted the argument and restarted, and ore still goes through the portal. That is not a typo in your launch line. On a dedicated server every world modifier is a launch argument (-preset, -modifier, -setkey), and the world also saves the modifiers it was started with, so removing an argument does not undo it. The reset is a preset in front (-preset normal, then only the modifiers you want), because in Iron Gate's words a preset "will overwrite any other previous modifiers". This guide lists every value Iron Gate documents, the ordering rule, what we found inside a world's save file, and what the groups on our own servers actually change.

What are world modifiers, and how does a server set them?

World modifiers arrived in Patch 0.217.14 on 22 August 2023, as a button on the start-game screen to "select a preset or design your own". Dedicated servers got them properly in Patch 0.217.22 on 5 October 2023, "using parameters in the startup batfile … or using the console as an admin". There is no menu on a server, so you use three arguments:

Values are lower-case single words: veryhard, not "Very Hard". A typo or a space inside a value and the server ignores it.

Every modifier and its values

This is the complete list in Iron Gate's dedicated server guide:

There is no normal value. Leave a modifier out and it runs at whatever the preset sets, or at Normal with no preset.

Portals: what each value really does

Portals is the modifier our customers ask about, so we read these straight out of the game's own text on one of our servers:

hard is about boss fights. It is not a stricter ore rule. If you want the normal item restrictions back after trying casual, you want no portals modifier at all, applied with the reset in the existing-world section below.

Presets

Seven, per the guide: normal, casual, easy, hard, hardcore, immersive, hammer. Iron Gate does not publish what each preset sets slider by slider, and the preset tables you will find elsewhere have no source. Two things are documented:

• Hammer blocks some achievements. The 1.0 FAQ: "Some world modifiers such as hammer-mode will also block certain achievements. Hammer-mode counts as a temporary cheat."
• Immersive includes fire spread. Patch 0.218.15 (Ashlands) added "a new world modifier that allows fire to spread outside of the Ashlands as well (part of the immersive preset)".

The guide also says: "Setting a preset will overwrite any other previous modifiers." That one sentence is the key to the rest of this page.

The four keys, and two the guide doesn't list

Iron Gate's server guide is dated 11 April 2024, and two modifiers have arrived since: the Ashlands fire-spread option, and No Craft Cost, which Patch 0.219.16 (19 November 2024) split out of No Build Cost. The guide gives no server argument for either, so we are not going to guess one.

The order that silently undoes your settings

The guide on -modifier: "If combined with a preset should be set after." A preset overwrites what came before it, so:

# Works: hard preset, raids switched off
-preset hard -modifier raids none

# Does not: the preset comes last and puts raids back
-modifier raids none -preset hard

A complete Linux launch line:

./valheim_server.x86_64 -nographics -batchmode \
  -name "Odin's Rest" -port 2456 -world "Midgard" -password "changeme1" \
  -public 1 -crossplay \
  -preset normal -modifier resources more -modifier portals casual -setkey playerevents

When a modifier is applied, the server log prints a line such as Setting world modifier: portals->casual. No line, no modifier. The rest of the launch line is covered in the dedicated server setup guide. If you would rather never touch a launch line, every one of these is a dropdown on a Connect Valheim server, written preset-first so the order cannot go wrong.

Can you change world modifiers on an existing world?

Yes. Stop the server, change the arguments, start it again, and the same world loads under the new rules. What catches people is the opposite direction: taking a modifier away.

In September a customer's ores kept teleporting after portals had gone from casual to hard to no argument at all. We downloaded the world's newest _main.N.fwl2 from saves/worlds_local/<World>/ and found it still listing teleportall and nobossportals, plus one preset entry appended for each start. Nothing had ever been removed. A start line without a preset adds to what the world already holds. LOW.MS's documentation describes the same behaviour.

So, to change or remove modifiers on a world you already play:

1. Back up the world folder in worlds_local first.
2. Lead with a preset. Use -preset normal (or your chosen preset), then only the modifiers and keys you want. A preset "will overwrite any other previous modifiers", in Iron Gate's words.
3. Or start once with -resetmodifiers. Iron Gate added it in Patch 0.217.22. Host documentation says it resets on every start you leave it in, so take it out again afterwards. We have not re-tested it on 1.0.
4. Check the log for the Setting world modifier: lines you expect, and have everyone rejoin.

Boss progress is stored separately: in that same world the boss kills (defeated_* keys) sat in the .db2 world data, not with the modifiers. An admin can also do it live from the F5 console. Patch 0.217.22 lists setworldpreset, setworldmodifier, setkey, removekey, resetworldkeys and listkeys, the last of which "displays list on dedicated server". We have not re-tested these on 1.0. Host documentation warns that resetkeys also clears boss kills, so use resetworldkeys instead.

One 1.0 note: Patch 1.0.21 (28 October 2026) fixed "some achievements … incorrectly tied to the current difficulty level": Mighty Halls, Comfort is King, The Homesteader, The Architect and The Survivor. If a harder or easier world was blocking one of those, update and try again.

Which modifiers do groups actually use?

On 29 October 2026 we counted the 86 active Valheim servers we host. 53 run at least one modifier. What they changed:

Not one server lowers the resource rate, and only four make combat harder. On our fleet, modifiers are mostly used to cut the grind. If you want a starting point, the two most common changes are a higher resource rate and portals casual.

Setting world modifiers on a Connect server

1. Open your server's Server Settings tab and scroll to World modifiers.
2. Pick a Preset, then set any of Combat, Death penalty, Resource rate, Raids and Portals. Preset default means "leave it to the preset".
3. Switch on any of No build cost, Player-based raids, Passive enemies and No map.
4. Save changes, then Restart now. Players are disconnected and the join code changes.

To clear a modifier you set earlier, put its dropdown back to Preset default and make sure a preset is written: if the menu already shows Normal, pick another preset and then Normal again before saving, so the server starts with -preset normal. If an old rule is still in force after the restart, open a ticket and we will reset the world's saved modifiers for you.

Frequently Asked Questions

Can you change world modifiers on a dedicated server?

Yes. They are launch arguments (-preset, -modifier, -setkey). Change them and restart, and the existing world loads with the new rules. Put the preset first.

Why is a Valheim modifier still active after I removed it?

The world saves the modifiers it was started with, and a launch line without a preset only adds to them. Start once with -preset normal followed by only what you want, or with -resetmodifiers, then restart.

Why aren't my world modifiers working on the server?

Usually the -preset comes after the -modifier and resets it, or a value is misspelt (very hard instead of veryhard). Check the log for a Setting world modifier: line.

Do world modifiers turn off achievements?

Hammer does: Iron Gate's FAQ says it "counts as a temporary cheat" and blocks certain achievements. Patch 1.0.21 fixed five achievements that were wrongly tied to the difficulty level.

Does portals hard stop ore going through portals?

Not by design. The game describes hard as "you will not be able to use portals or exit boss dungeons while a boss is active", which says nothing about items. To go back to the normal portal rules after casual, remove the portals modifier and reset the world's saved modifiers.

How do I turn raids off on a Valheim server?

Add -modifier raids none after any -preset and restart. On a Connect server, set Raids to None on the Server Settings tab.