Factorio: Fixing Multiplayer Desyncs
"Desynchronization" happens when your client thinks the game state is X, but the server says it is Y. Factorio is deterministic; if 1+1 doesn't equal 2 for everyone, the game kicks you to reload the map.
1. The Desync Loop
If you join, play for 10 seconds, get dropped, and reload—you are in a desync loop. This is usually caused by a incompatible mod or corrupt map data.
2. The Desync Report
Factorio generates a desync-report zip file when an error occurs. This contains the technical data needed for developers to fix the issue.
3. Heavy Mode
A debug mode that forces the game to double-check every calculation. This is the ultimate tool for finding which specific mod is causing logic errors.
Common Causes & Fixes
1. Mod Mismatch (The #1 Cause)
Even if version numbers match, a "local" modification to a mod's Lua files will cause desyncs.
- Fix: In the server browser, check "Sync mods with server". This forces your client to download the exact zip files the server is using.
- Fix 2: Delete your
modsfolder locally and let the game re-download them fresh.
2. The "Remote View" Bug (Space Age)
In Factorio 2.0 (Space Age), using Remote View on large planets can trigger desyncs if the server optimization settings differ from the client.
- Fix: Ensure both server and client are running the exact same version (e.g., 2.0.15). Do not mix Stable client with Experimental server.
3. Analyzing the Desync Report
When you desync, a folder is created in your Factorio directory (/archive/desync-report-...).
- Open the
level-tick-xxxx.datinfo (requires technical knowledge). - Easier Solution: Upload the report to the Factorio Forums under Bug Reports. The developers are very active and can often identify the culprit immediately.
Debugging for Admins
If you are a server admin and the map keeps crashing users:
- Start the server with the flag:
--check-consistency. - Use the console command:
/c game.force_crc()to force a consistency check immediately. - If you suspect a specific mod, try disabling recently added script mods (mods that change game logic, rather than just adding new items).
Stay synchronized. View plans.