Factorio 2.1 Stable Server Guide: Upgrade, Mods & Rollback

Factorio 2.1 Is Stable: Moving Your Server From 2.0, Mods, and Rollback

Last verified: October 23, 2026 against Factorio's release API, Friday Facts #449 and the shipped 2.1.23 headless package. Wube marked 2.1 stable on 23 October 2026; stable and experimental both carry 2.1.23.

Factorio 2.1 is the stable release. Wube marked it stable on 23 October 2026 after a summer in experimental, and envisions it as its last major update, with long-term support to follow. Steam's default branch moved to 2.1.23 the same day, so players whose client updated are turned away by a server still on 2.0 until it moves too. For the save the move is one way, and it is hard on old mods. This guide covers what changes for a dedicated server, how to protect the world, and how to stay on 2.0 if your group needs to.

What 2.1 is (and deliberately is not)

Wube scoped 2.1 as quality of life, small features, polish, and modding improvements, ruling out new planets, enemies, research trees, and resource chains. One substantial area is space logistics (Friday Facts #441):

• Automatic rockets can mix item types for platform construction. They may still overdeliver an item to fill a rocket, so do not assume every delivery matches the requested count exactly.
• Platform construction requests prioritize foundation and cargo bays before other materials.
• Leaving a request's Import from field blank allows pickup from all locations; set a planet when the source matters.

These shipped with 2.1 and are in the stable release. Wube explains the rocket batching and request rules in Friday Facts #441. Keep the server, clients and mods on the same build.

Stable, experimental, and staying on 2.0

• Stable is 2.1 now. factorio.com's stable headless download and Steam's default branch both serve 2.1.23. The experimental branch carries the same build for now; a new 2.1 point release usually appears there first.
• Version match is absolute. Clients and server must run the same version. Steam moved its default branch to 2.1.23 on 23 October 2026, so a server still on 2.0.77 turns away every player whose client updated. Move the server and the players together.
• Staying on 2.0 is still possible. Steam keeps a 2.0.77 beta branch for clients, and factorio.com still serves the 2.0.77 headless build, so a group whose mods are not ready can pin both ends to 2.0.77 and move later.
• Experimental iterates fast. During an experimental cycle, point releases can land several times a week. Headless servers either chase them (auto-update and announced restarts) or pin one build and update deliberately. Pin; chasing is for test servers.

What the 2.1.23 headless package contains

The stable headless package reports 2.1.23, internal build 87750, linux64, headless, with map output version 2.1.23-2; 2.0.77 reports 2.0.77-0. Its map input version is 1.0.0-0, so 2.1.23 opens saves from 1.0 onward. Back up the save before moving; the map output version also makes the version gap visible.

The mod list grows from five to six

2.0.77 ships five bundled mods: core, base, elevated-rails, quality and space-age. 2.1.23 ships six. Recycling moved out of the quality mod into the bundled recycler mod; quality and space-age both depend on it, while quality itself became a recommended dependency of Space Age rather than a required one, which is how 2.1 lets Space Age run without Quality.

Three consequences for a server:

• Name recycler in a hand-written mod-list.json. When the list leaves it out, 2.1.23 adds it as enabled on its own, and it did so even when we started it with a 2.0-style list that switches every expansion mod off. recycler is one of the expansion mods, so set it to true with Space Age and to false on a server meant to be vanilla.
• Any mod that touched recycling prototypes is touching a different mod now. This is a concrete reason to put recycling-adjacent mods at the top of the audit list below rather than treating the whole list as equally risky.
• The bundled mods gained a new marker. On 2.1.23 the four expansion mods, elevated-rails, quality, recycler and space-age, declare expansion_required; the 2.0.77 versions do not.

The base game is nearly untouched, and that is the point

With only base enabled, 2.1.23 resolves 217 recipes, 196 technologies, one planet and 245 items, against 2.0.77's 217 recipes, 196 technologies, one planet and 244 items. Those counts show little change to vanilla prototypes; they do not establish that every gameplay or save behavior is unchanged. Test the exact save and mod set before moving a server.

Four new launch arguments

The option parser prints its own registry, so the argument list is comparable between builds directly. 2.1.23's registry names four arguments 2.0.77's does not:

--exchange-string is the useful one for anybody starting a server. It takes the map exchange string you copy out of the map generator screen and applies it directly at world creation, which removes the whole step of translating an exchange string into a hand-written map-gen-settings.json. Note the ordering the parser states: the exchange string is loaded first, then any other settings arguments are processed on top, so you can use one as a base and override a single value.

The Server argument group still has thirteen arguments on 2.1.23, word for word the same as on 2.0.77, alongside 53 console commands, 19 /config settings and 28 documented server-settings.json keys. These registry counts do not by themselves prove identical network behavior. Check port configuration and server settings when moving a server.

The no-downgrade rule

The single most expensive mistake of a major update: saves do not load backwards. Wube's 2.1 notes say it plainly: once updated, saves and blueprints cannot be taken back to 2.0. The binary downgrades fine; your two-hundred-hour map does not. So:

• Copy the save file itself before switching: a real file copy you control, not only a panel snapshot you have never restored.
• Keep the 2.0 backup until the group commits. If 2.1 goes badly (a mod you depend on lags, a bug bites your base), the rollback is: put 2.0.77 back on the server and on every client, restore the save, and lose the sessions played on 2.1. Decide in advance whether that trade is acceptable, and tell your players.

Mods: audit before you flip

A mod built for 2.0 stops a 2.1 server from starting. Each mod names the game version it targets in the factorio_version field of its info.json, and 2.1.23 refuses one that still says 2.0 with Incompatible Factorio version (current: 2.1, required: 2.0). We checked by starting 2.1.23 with a test mod marked 2.0: the whole start failed, not just that mod, and the same mod marked 2.1 loaded. So before the server moves, export your mod list, check each mod's portal page for a 2.1 release, and classify each as critical, nice-to-have or droppable; a mod with no 2.1 release has to come out. Wube says most popular mods were updated during the experimental period and that some you rely on may not be ready yet. Put recycling-adjacent mods first in the audit, since recycling now lives in a mod of its own. A server whose permissions or protection mod is "droppable" has a different definition of droppable after the first griefing. Our mod installation guide covers the per-version mechanics.

2.1 brought the ARM64 Linux build, headless included

Friday Facts #446, 18 September 2026, shipped something a host cares about more than the space logistics work: "Standalone Factorio for ARM64 Linux is available on our website, including the headless version." On Steam it first shipped on the experimental branch, which Wube asked ARM64 players to opt into. Since 2.1 went stable on 23 October 2026, Friday Facts #449 lists native ARM64 Linux among what the stable release brings, naming the Steam Frame and Raspberry Pi headless servers. So an ARM box, a Raspberry Pi or an Asahi Linux MacBook can run the server on the stable release, with everything above about mods and rollback still applying.

On whether ARM and x86 players can share a world, the only evidence Wube has published is their own testing: "we never experienced an ARM64 vs. x86 related desync" across the May 2026 LAN party, credited to the earlier Nintendo Switch and Apple Silicon ports. That is a report of an absence, not a compatibility guarantee, and the post makes no statement at all about save files moving between architectures. Our own nodes are AMD x86, so nothing here changes a server you rent from us.

The decision matrix

• Fresh group starting now: start on 2.1.23, the stable release, unless a mod you need has no 2.1 release yet. Dial in map-exchange settings with the Factorio map generator before world creation.
• Active long-running save, vanilla: load a copy of the save on 2.1.23 first and check your circuit builds, because 2.1 replaced the old self-subtraction with separate input and output wires and Wube warns that this may break existing designs. Then move with a verified backup; your players' Steam clients are already on 2.1.
• Active save, heavily modded: stay on 2.0.77, on the server and on every client through Steam's 2.0.77 beta branch, until every critical mod has a 2.1 release that survives testing on a copy of the save.
• Archival megabase: there is no need to move while 2.0.77 meets your needs, as long as everyone who joins stays on 2.0.77 too. Wait until the save and every critical mod work on 2.1. The update mechanics are in how to update your server.

Want the version switch to be a dropdown instead of a package swap? Host a Factorio server with Supercraft: pick the branch in the panel and keep a backup from before the move.

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