Everyone who joins a Factorio server needs the same mods as the server, in the same versions. The game’s own manual says “all game instances need the installation of exactly the same game-versions and mods.” If one mod is missing or on another version, that player cannot join, or is sent back to rejoin.
See what the server has
- Open the Mods page and the Installed tab.
- Read the list. A row shows its version and a chip: Loaded, Off, Refused, or Not started yet.
- Mods that are Off are skipped from the next start. The player does not need them.
- Under Wube’s own (2), check Space Age, Quality, Elevated rails and Recycler. The page says it when Space Age is on (1): “players need the expansion to join.”
The chips say what the game did at its last start. Loaded means the game used the mod.
- Space Age note
- Wube's own
Make the player match
- In the player’s game, open the Mods menu.
- Install every mod that is Loaded on the server, in the same version as the server’s row.
- Turn off any mod the server does not have.
- Join again.
Or make the server match the players
Updating a mod downloads it from the mod portal, so the server needs its factorio.com username on Startup and its token under Passwords. See the mod portal account.
- To use a newer version of a mod, open its row menu, More for (name), and choose Update to (version). Update all updates every mod that has a newer release.
- To drop a mod, switch it off with the switch on its row, Turn (name) off. The mod stays on the server and is skipped from the next start. Remove in the row menu deletes it.
- Changes apply at the next start. Use Restart at the top of the server page, then tell players to update their mods.
A mod for another game version does not load. See mod not for this version.
If it does not work
- The list looks the same but the player still fails. Check version numbers one by one. A mod can have a newer release on the mod portal than the player’s copy.
- Only Space Age players fail. They need the expansion. If some players do not own the expansion, you can turn Space Age off under Wube’s own, after the warning above. If nobody has played yet, a new world made on the World page after turning it off is the clean way. Turning off Quality, Elevated rails or Recycler also turns Space Age off.
- A mod shows Refused. The game refused it at its last start. The page says which. Update it or turn it off.
- The player joins, then gets sent back. Their game stopped matching the server. A mod is the usual cause.
- What the player sees. Not checked on 2.1.24 as of 13 November 2026: the game’s exact refusal text, whether the game offers to fetch missing mods itself, and whether Quality, Elevated rails or Recycler need the expansion when Space Age is off.
More about mods on a server: Factorio mods. More about the game: Factorio servers.
Sources: wiki.factorio.com: Multiplayer