Installing and Managing Mods
How to install, enable, and manage mods on a Factorio dedicated server, including the critical client-server sync requirement.
Overview
Factorio has a rich mod ecosystem hosted at mods.factorio.com. Server-side mods affect gameplay for all players. Understanding the sync requirement between server and clients is critical — getting this wrong is the most common cause of connection failures.
Critical: Mods Must Match Exactly
Every client connecting to your server must have the exact same mods and mod versions as the server. If there is any mismatch, the client will be refused with a "Mod mismatch" error. This includes:
- A mod present on the server but not the client.
- A mod present on the client but not on the server.
- The same mod at different version numbers.
There is no partial-match fallback. The match must be exact. Plan your mod list carefully before inviting players, and communicate any mod updates to all players before applying them server-side.
Mod File Location
Mod .zip files go in:
factorio/mods/
Upload mods via the panel Files tab. Do not extract mod zips — Factorio reads them as-is.
mod-list.json
This file tells the server which mods to load:
{
"mods": [
{ "name": "base", "enabled": true },
{ "name": "SomeModName", "enabled": true },
{ "name": "AnotherMod", "enabled": false }
]
}
Rules:
- The
"base"mod must always be present and enabled. It cannot be disabled. - Any mod in
mods/that is not listed here will not be loaded. - Any mod listed here that is not in
mods/will cause a startup error.
After editing mod-list.json, restart the server.
Installing a Mod
- Download the mod
.zipfrom mods.factorio.com. - Upload the
.ziptofactorio/mods/via the panel Files tab. - Add the mod to
mod-list.jsonwith"enabled": true. - Stop and restart the server.
- Distribute the same mod
.zipto all connecting players and have them enable it in their mod manager.
mod-settings.dat
This binary file at factorio/config/mod-settings.dat stores per-mod configuration values. Do not edit this file manually — it is a binary format and will be corrupted if opened as text. Change mod settings via the in-game options menu while connected to the server (as admin), or locally in a singleplayer session and then copy the file.
Disabling a Mod
Set "enabled": false in mod-list.json for the mod, then restart. Disabling a mod that affected map state (added buildings, entities, etc.) can corrupt or change the save. Test on a copy first.
Major Version Updates and Mods
When Factorio releases a major version update, many mods become temporarily incompatible. Check mods.factorio.com to verify a mod supports the new version before updating. If a mod has no update for the new version, you must either wait, remove the mod, or stay on the old server version. See Updating the Factorio Server and Managing Compatibility.