Valheim 1.0 has been out since 9 September, the launch rush has calmed down, and some servers are still carrying a problem from that first week that nobody's noticed yet. A friend can't get in and nobody knows why. The world folder looks nothing like the guide you followed last year. Someone took a fully upgraded sword off an item stand and it came back with its upgrades gone.
None of that is a disaster. It's a checklist. We've hosted Valheim since the game launched in 2021 and spent launch week reading a lot of 1.0 server logs, so here's what I'd go through on any server now that 1.0 is out, roughly in order. Most of it takes a few minutes. A couple of items are genuinely easy to get wrong, and I've flagged those.
Check you're on 1.0.12, not the launch build
Iron Gate didn't stop at launch. The build that went out on 9 September reports itself as 1.0.7 in the server log, and two days later, on 11 September, they shipped hotfixes 1.0.10 and 1.0.12. The dedicated server build now on Steam is 1.0.12.
Here's the catch, and it's the one that keeps catching people: restarting your server does not update it. A restart just starts the same build again. So a server that was updated on launch day and restarted every night since can still be sitting on 1.0.7 while every player's Steam client has moved on. The two report different network versions (39 on the launch build, 40 on 1.0.12), which is exactly the sort of gap that turns players away at the door.
On the LOW.MS panel it's quick to fix:
- When a newer build is out, an Update button appears on the bar at the top of your server's page, beside the power buttons. Press it and confirm. It stops the server, pulls the new build, puts your installed mods back and starts it up again.
- The Settings tab shows the same thing under Version, with an "Update available" marker if you're behind.
- If you'd rather not have to remember, go to Scheduled tasks on the Settings tab, click Add schedule and pick the Update task. Early morning, a couple of times a week, is plenty for most groups.
Your Steam players need to be on the same build (1.0.12 is a Steam hotfix, and Iron Gate say it's fully crossplay compatible), so if someone on Steam still can't join after you've updated, ask them to restart Steam and let the game patch.
If your Valheim server is still on our older panel at control.low.ms, Steam Update in the sidebar does the same job. The game advice below holds there too, but the tab names and paths are for our new panel, so open a ticket if you can't find the equivalent.
Take a backup you control
If you haven't already got a backup from after the update, take one now, before you touch anything else on this list.
Valheim keeps its own rolling backups next to the world (four by default, set in the Saves & Backups group on the Manage tab), and they're fine for a crash mid-save. They won't help with the slower sort of problem, the one someone notices three days later, because by then the rolling set has rolled past it.
So use ours as well. Create backup on the Backups tab writes a copy off the server, and restoring is on the same tab. Lock the one you took just after updating so it never gets deleted to make room. Then add a Backup task under Scheduled tasks while you're there. It's five minutes, and I'd much rather you set it up on a quiet evening than go looking for it after something's gone wrong.
Your world is a folder now
This is the big change most guides online still haven't caught up with, including a few of ours while we work through them.
Before 1.0 a Valheim world was a pair of files, a .db and a .fwl. 1.0 ships a new save system that splits the world into chunks, so only the parts that changed get written, and it's built to survive a save being cut off halfway. On your server, open the Files tab and go to config/valheim/worlds_local/. A world now lives in its own folder named after it, full of .chunk files plus a few _main files.
If your world is older than 1.0, you'll also see what the conversion left behind the first time it loaded:
YourWorld.db.oldandYourWorld.fwl.old, which are the original files, renamedYourWorld_backup_followed by a date, a.dband.fwlcopy the game made just before converting- your pre-1.0 auto-backups, still as flat files, untouched
Leave the folder alone. If you want to download the world, or restore one by hand, the whole folder is the unit now, not a pair of files. Grabbing a single .chunk or the old .db.old will not give you your current world. Valheim's own auto-backups also became folders, named YourWorld_backup_auto- with a date and time.
Gotcha: the World Name suggestions on the Manage tab still look for the old file format, so for now they won't list a 1.0 world, and they can even tell you your world doesn't exist when it's sitting right there in the folder. Leave World Name as it is. If the only suggestion offered ends in _backup_ and a date, that's the snapshot from just before conversion, and picking it would load your world as it was on launch day. We're fixing the picker.
Don't take good gear off item stands without a backup
Worth reading if your group had trophy weapons and armour on display.
Early on, items on armour stands and item stands in worlds that had been loaded on 1.0 could lose their durability and upgrade level. The 1.0.12 hotfix stops that for worlds that hadn't yet been loaded on 1.0, but Iron Gate say they're still looking into a better fix, and their advice for anyone who's already been playing 1.0 is not to remove high-level items (weapons, armour, fish and the like) from stands without a backup. So take one first, as above.
Ban lists and whitelists
1.0 uses a new player ID format (Iron Gate's example is V_123456789) alongside the old Steam_ style. On the launch build, ban lists and whitelists only recognised the new format, so old-style entries didn't work. 1.0.12 fixed that, and both formats work again.
If someone you banned turned up during launch week, or a whitelisted friend got refused, that could well be this. Update to 1.0.12 (see the first section) rather than rebuilding your lists on the Players tab.
Mods need 1.0 builds
Iron Gate were upfront that they couldn't guarantee any mod would work at 1.0, and there was no public test branch for 1.0 itself (only the new save system had a public test, back in May), so most mod authors met the full build on launch day like everyone else. The Unity engine was updated too, on top of a lot of game code changing, so plugins that were fine the day before can break.
My order, if a modded server is misbehaving:
- Get it running vanilla first. A clean start tells you the build is fine and the problem is a plugin, which is a far shorter conversation.
- Check each mod's Thunderstore page for a release made after 9 September before you put it back.
- Add them back from the Mods tab a few at a time, restarting in between.
Anything that reads or writes world files directly, world editors and save tools especially, needs a version built for the new folder format. An old one won't understand the chunks.
One myth to put down while we're here, because we used to repeat it ourselves: turning crossplay on doesn't stop BepInEx loading. What does bite is that console players can't run client-side mods at all. There's a longer triage write-up in Valheim Mods After the 1.0 Update.
Crossplay, and the Switch 2 exception
Valheim 1.0 has crossplay across every platform it's on, which now includes PlayStation 5 and Nintendo Switch 2. On our panel it's one tick: Crossplay in the General group on the Manage tab, save, restart. Console and Game Pass players then join with a six-digit code shown on your server's Overview tab, and that code changes every time the server starts, so check it again after a restart or an update.
Now the exception. The 11 September hotfix couldn't be uploaded to Switch 2, and Iron Gate say crossplay between Switch 2 and the other platforms isn't currently supported until it is. Their workaround is for Steam players and dedicated servers to switch to the default_old branch, the previous build. Our panel doesn't offer a branch switch for Valheim, so if your group genuinely needs default_old, open a ticket. Think about it first, though. Iron Gate's workaround moves your Steam players onto the old build as well, which tells you a mixed group won't connect. Iron Gate also say there's no workaround at all for PlayStation 5 and Xbox players with Switch 2, and rolling back gives up the 1.0.12 fixes, ban lists and item stands included. Unless the Switch players are most of your group, I'd wait for their patch.
The join code walkthrough, and the handful of things that reliably go wrong with it, are in Valheim Crossplay and Join Codes.
Old world or new world for the Deep North
Iron Gate's 1.0 FAQ is clear: an existing world does get the new content, but biome generation only works properly on areas nobody has explored yet. Anything the game already generated in explored areas stays as it was, so if your group has already been to the far north, that ground won't change, and the new content shows up in the parts of the map you haven't reached.
Iron Gate still recommend starting over. That's your group's call, and I wouldn't make it for you, but make it before people sink another fifty hours into a world that can't give them the biome where they expect it. The trade-offs, including the mod route for regenerating explored ground, are in Deep North on an Existing Valheim World.
If you do want a fresh 1.0 world, open a ticket and we'll set it up. The panel's own New World tool was written for the old file format, and until that's updated for 1.0 folders I'd rather do it with you than have you find out it didn't clear the old world.
Achievements and devcommands
1.0 added achievements, and Iron Gate's FAQ says using most devcommands places a flag on your current character and world save that locks them out of achievements. Hammer mode counts as a temporary cheat. That matters on a dedicated server, where admins who want devcommands run a mod for them.
The 1.0.12 hotfix softened it: there's now a devcommand that lets you opt back into achievements even after using devcommands or mods. Still, if your group cares about them, have a word with your admins before anyone starts spawning replacement gear.
What didn't change
Handy to know, because it rules things out when you're troubleshooting. Iron Gate's 1.0 and hotfix notes list no new or changed launch arguments for dedicated servers, and the server still honours the same backup settings it did before. The player limit is still 10.
If something on this list doesn't match what you're seeing, or your server won't come up after an update, open a ticket and we'll read the log with you. If you're standing up a new group for 1.0, the Valheim hosting page is the quick route, and for the wider picture of what 1.0 means for dedicated servers there's Valheim 1.0: What Changes for Dedicated Servers.
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