Factorio Server Saves and Autosaves

A Factorio server runs exactly one save file, and that file is the only thing that matters if anything goes wrong. Autosaves rotate on a fixed cycle and overwrite each other, so they are a rollback mechanism rather than a backup. This page covers where the save lives on your server, how the autosave cycle actually works, how to bring your own world across, and what a real backup looks like.

The short version

Your world is the .zip at the root of your file tree, named by the Save Name field — gamesave.zip by default. Autosaves cycle through 5 slots and will eventually overwrite themselves. Before anything risky, download a copy to your own machine. That is the backup.

Where the Save Lives

Read it straight off the startup line your Factorio server runs:

./bin/x64/factorio --port <your port> --server-settings data/server-settings.json --start-server gamesave.zip

--start-server is followed by the save path, and on your server that path is gamesave.zip at the root of the file tree — beside bin/, data/ and mods/. It is not inside a saves/ folder, which is where Factorio puts saves on a desktop install and where most guides will tell you to look.

The name comes from the Save Name field on the Startup tab. Change that field to bigfactory and the server will look for bigfactory.zip. Note the field takes the name without the .zip extension — the startup line appends it.

Why the Save Must Exist Before the Server Starts

The headless build cannot generate a world at boot. The official wiki is explicit: "You will need to create your save file before you start the server, as the dedicated server REQUIRES a save file to be provided."

Your installation handles this, running the documented --create step against your Save Name value. The consequence to remember is what happens if you point Save Name at a file that does not exist: the server will not start, and the console will say it cannot find or open the zip. That is the correct error, not a fault — check the filename in the File Manager, including case and the missing .zip.

The Autosave Cycle

Two settings drive it, and Wube documents both in the shipped server-settings.example.json:

"Cycled through" is the important phrase. With 5 slots and a 10-minute interval you hold roughly 50 minutes of history. The sixth autosave overwrites the first. If a mistake goes unnoticed for an hour — a misfired deconstruction planner, a train rerouted into a smelter column — the autosaves have already rotated past it.

Two more behaviours are worth knowing:

• The headless server "Saves the game on exit (and autosaves normally)", per the wiki. A clean shutdown through the panel writes the world out; the stop command is /quit, which is the graceful path.
• The game "is paused while there are no players connected" unless you disable auto_pause. A paused server does not autosave, because no ticks are passing. An empty server is not quietly churning through its autosave slots.

Save on demand before anything risky

/server-save from the panel Console writes the world immediately. Run it before installing a mod, before a version change, and before letting a new player loose with a nuke. It costs a few seconds and it does not consume an autosave slot.

Autosave Options in server-settings.json

Two keys change how saving behaves, and neither is exposed as a Startup field — edit them in data/server-settings.json:

autosave_only_on_server (default true) — Wube: "Whether autosaves should be saved only on server or also on all connected clients. Default is true." Left on, your players' machines are not writing copies of your world. Turning it off gives every connected client a local copy, which is an accidental distributed backup and also a way to annoy everyone with periodic stutter.

non_blocking_saving (default false) — the one setting in the file Wube warns about in its own comment: "Highly experimental feature, enable only at your own risk of losing your saves. On UNIX systems, server will fork itself to create an autosave." On a large factory it removes the freeze every player feels when the server saves. The trade is stated plainly in that quote.

autosave_interval and autosave_slots are both managed by the panel, so changing them in the file does nothing that survives a restart. Use the Auto Save Interval field.

Uploading a World From Your Own Game

Bringing across a single-player save, or a world your group started on someone's PC, takes four steps.

1. Find the save on your machine. The official wiki gives the user data directory per platform: %appdata%\Factorio on Windows, ~/Library/Application Support/factorio on macOS, ~/.factorio on Linux. Saves are in the saves subfolder as .zip files.
2. Check the version. The wiki's compatibility ladder caps each build at saves "up to" its own version — 2.0.x "loads saves from 1.0.0 up to 2.0.x" — so a world from a newer build will not open on an older server. Match the server to the save, not the other way round.
3. Stop the server, then upload the zip to the root of the file tree through the File Manager.
4. Set Save Name to the filename without .zip and start the server. Watch for Hosting game at in the console.

Mods travel with the world, not inside it

A modded save will not load unless the same mods are present in mods/ on the server. Upload the zips too — see how to install Factorio mods, which covers why the server will not fetch dependencies on its own.

What a Real Backup Looks Like

Autosaves protect you from the last hour. They do not protect you from a corrupted file, a bad mod removal, or someone with admin rights and bad judgement — all of those get autosaved straight over the top.

The official wiki's own advice, in the context of upgrading: "It is recommended to create backups from this directory (of saves, config, etc) before installing a new version."

A workable routine:

• Run /server-save, then download the zip to your own machine. Off-server is what makes it a backup.
• Do this before every version change, every mod change, and on a schedule that matches how much progress you would accept losing.
• Keep the old copy. A save is a few megabytes; a 200-hour factory is not replaceable.

Common Questions

Where are the autosave files?

In the server's saves folder, written by the game itself rather than by the startup line. Open the File Manager and look there — the rotation means the names cycle, so sort by modified time to find the newest.

How do I roll back to an autosave?

Stop the server, copy the autosave you want to the root of the file tree, rename it to match your Save Name, and start. Keep the file you are replacing.

Can I run more than one world on the same server?

One at a time. Upload both zips, and switch by changing Save Name and restarting. The inactive world is untouched.

Does changing Save Name create a new world?

No. It changes which existing file the server loads. If no such file exists the server will not start.

Why is my server freezing every few minutes?

That is the autosave on a large map. Lengthen Auto Save Interval, or read Wube's warning on non_blocking_saving above and decide whether the trade is one you want.

Do autosaves survive a reinstall?

Assume not. A reinstall rewrites the server files. Download anything you care about first.

What to Read Next

• How to Set Up a Factorio Dedicated Server — first boot and the file tree
• Factorio server-settings.json: Every Setting Explained — the saving keys in context
• How to Install Factorio Mods on a Dedicated Server — why a modded save needs its mods uploaded too

Made with 💜 by GameServerKings