Tuning Autosave Settings and Recovering from Backups

Overview

Factorio's built-in autosave is your first line of defense against data loss. Configuring it correctly means the difference between losing 10 minutes of progress and losing hours of work.

Autosave Configuration

Both settings live in server-settings.json:

{
  "autosave_interval": 10,
  "autosave_slots": 5
}

• autosave_interval — Minutes between autosaves. Default is 10. Set to 0 to disable autosaves entirely (not recommended for production).
• autosave_slots — Number of autosave files to keep. When the slot limit is hit, the oldest autosave is deleted and a new one is written.

Choosing the Right Values

Recommended baseline for active servers:

{
  "autosave_interval": 10,
  "autosave_slots": 5
}

This gives a 50-minute rolling backup window (5 slots × 10 min).

More aggressive backup:

{
  "autosave_interval": 5,
  "autosave_slots": 10
}

50-minute window with finer-grained recovery points.

For large maps (performance consideration): Autosaves cause a brief UPS dip on large maps because the server must serialize the entire game state. If players notice hitches every 10 minutes, increase autosave_interval to 15 or 20. The save operation itself is threaded in recent Factorio versions, but very large maps can still stutter.

Autosave File Names

Autosaves are written to factorio/saves/ with names like:

autosave_1_20260427T143022Z.zip
autosave_2_20260427T153022Z.zip
autosave_3_20260427T163022Z.zip

The slot number cycles. The newest autosave is not necessarily the highest-numbered slot — check the file modification timestamps in the panel Files tab to identify the most recent save.

Recovering from an Autosave

If you need to roll back to an autosave:

1. Stop the server via the panel.
2. Open the Files tab and navigate to factorio/saves/.
3. Identify the autosave you want to restore (use modification timestamps).
4. Copy or rename it to a new file, e.g., recovered.zip. This preserves the autosave in case you need to try a different slot.
5. Update the startup save variable (SAVE_NAME) to recovered.zip in the Startup tab.
6. Start the server.

Alternatively, copy the autosave file name directly into SAVE_NAME:

autosave_3_20260427T163022Z.zip

Preventing Autosave Loss During Updates

Before applying a server update, download the latest autosave from the Files tab as an off-panel backup. Factorio saves forward-compatible but the first load on a new version modifies the file — having an untouched copy is a safety net.

See Updating the Factorio Server and Managing Compatibility for full update procedures.

Related

• Managing Save Files and Autosaves
• Configuring Your Server with server-settings.json
• Updating the Factorio Server and Managing Compatibility
• Performance Tuning, UPS, and Player Capacity