Before you start
Record the game version, exact world name, connection backend and any mods. Schedule maintenance. Valheim’s official server guide describes parameters and files; actual locations depend on the server’s selected save directory.
Find the matching world files
A world called Midgard has a matching pair such as Midgard.db and Midgard.fwl. The .db file holds world data, while .fwl holds associated world information. Retrieve both from the same recovery point, avoiding files from different dates. For a cloud-stored world, use the game’s functions to obtain a coherent local copy before uploading it to a dedicated server.
Stop both sources of writes
Stop the world on the old host before taking the final copy. Stop the destination server too, so it cannot rewrite its own files while you replace them. Back up any existing destination world and configuration. Keep the source until validation is complete. A transfer made during an active save can be incomplete even when both expected filenames are visible.
Use the real save location
The CubixServ launcher selects /data/saves as its save directory and uses -world to choose the world name. Locate the actual worlds_local directory and existing file pair through the service’s files interface. Customer-visible paths may be relative to /data. Match the configured world name and filename case exactly. The public server name is not necessarily the world name used for file selection.
Confirm Steam or crossplay connections
Steam and crossplay backends have different connection behaviour. Crossplay uses the relay mechanisms described by Valheim and the -crossplay parameter; transferring a world does not enable it implicitly. Use the address and allocated ports shown by the panel. Do not change host network rules or assume standard ports are available. Check the selected backend before diagnosing an inaccessible server as a corrupted world.
Review access lists and mods
Check the password and the separate roles of adminlist.txt, permittedlist.txt and bannedlist.txt in the official documentation. Administrator membership is not a complete player access policy. Mods can require components on both client and server. A modded PC setup is not automatically compatible with console clients, even with crossplay enabled. Preserve the original mod environment and version details for troubleshooting.
Validate before reopening
Start the server, inspect logs and connect to check buildings, progression and world identity. Make a clean save and confirm files update in the expected directory. If a new world appears, recheck the world name, location and permissions before deleting anything. For rollback, stop the server and restore the matching file pair with its compatible configuration. Retain the previous backup until normal play has been verified.
For your situation
| Situation | Next check |
|---|---|
| A new world appears | Check the -world name, filename case and selected save directory. |
| Console players cannot join | Check the crossplay backend and mod requirements as well as the address. |
| Only one file is available | Retrieve its matching partner from the source or a coherent backup. |
Official sources
These documents describe the relevant protocols and software. Your service terms and configuration still need to be checked.