Stage a Factorio mod collection update and preserve a complete rollback
A successful mod update must load the factory correctly, keep its important systems intact and allow players to return. Treat the save and its mod collection as one release. This guide covers planned updates and recovery; the related mismatch article handles a player whose installed set differs from an unchanged server.
Freeze the working release
Record the full Factorio version, expansion requirements, enabled mods, exact mod versions and startup settings. Announce a maintenance window before interrupting players. Save and stop the service normally, wait for the process to finish, then make a complete backup that includes the selected save, mod files, generated mod list, settings and configuration.
Give the backup a clear date and retain it outside the active installation. Keep another copy of the current save separately. A backup containing only the factory cannot reproduce missing mod versions later, particularly if an author withdraws a release.
Build a candidate release
- Create an isolated test service or local installation using a copy of the factory. Keep its save output separate from production. Ask support for staging assistance if your plan does not provide another service.
- Read changelogs for the mods being changed and their dependencies. Check support for your Factorio major version and expansion features using the official metadata rules. A dependency update may affect more than the mod you selected.
- Update a documented group of compatible packages, preserving the original collection unchanged. Keep a small release note listing every changed file and version so you can explain precisely what was tested.
- Load only the copied save. Watch the earliest error and compare it with the author's upgrade instructions. Do not repeatedly disable content mods on the production factory to discover which combination starts.
Check the factory, not only startup
Factorio's migration system allows mods to transform saved data during loading. That means a save written after an update is a different recovery point from your untouched pre-update save.
Inspect representative production lines, modded machines, research and inventories. Check the systems your group relies on rather than trying to validate every entity manually. Join from a second client with the candidate collection, play briefly, save, stop and reload. Record any script errors or unexpected missing items before approving the update.
The official mod-sync guidance distinguishes synchronizing to a server from synchronizing to a save; the latter can select newer versions by default. Use your recorded package versions when reproducing a release instead of assuming every sync produces yesterday's collection.
Activate or recover as a complete set
If testing passes, repeat the controlled maintenance process on production with the tested packages and settings. Verify the production save selected by startup and confirm real players can join. Keep the pre-update snapshot and the candidate snapshot clearly separated.
If testing fails, preserve the failed candidate and its logs. Return the stopped service to the matching pre-update executable version, configuration, mod collection and untouched save, with support assistance where needed. Do not load the newly migrated save with older mods and call that a rollback. Check the restored factory and player connection before reopening access.