RimWorld Multiplayer Desyncs: Back in Sync Fast

The number one cause of desyncs. If even one mod differs between players – different version, load order, or a mod that isn't multiplayer-safe – you will desync. For example, a complex mod that isn't coded for MP might generate events or use random numbers that don't sync across clients.

Even having the same mod but different mod settings can throw things off. Always double-check that everyone's mod list is identical (the MP mod's interface will show a red icon if not). And when in doubt, disable mods that the RimWorld Multiplayer community hasn't vetted as compatible.

If one player is on RimWorld 1.5 and another on 1.4, you won't stay synced. The multiplayer mod will actually block connections if the version is obviously different (protocol mismatch), but if you forced it (or if a minor version differs), desyncs occur quickly.

Similarly, all players need the same DLC enabled. For instance, if the host has Royalty and Ideology and a client doesn't, the game state diverges whenever DLC content comes up.

This one is sneaky. RimWorld and many mods create config files (for settings, enabled mods, storyteller difficulty, etc.) on each PC. If Player A has different mod option settings than Player B – say, a mod like "Combat Extended" where you tweaked a damage setting – those differences can cause a desync when that setting comes into play.

The game might assume each client is applying the same rules, but if one has a slightly different XML config, boom – divergence.

Config Folder Locations:

• Windows: C:\Users\<You>\AppData\LocalLow\Ludeon Studios\RimWorld by Ludeon Studios\Config\
• Mac: ~/Library/Application Support/RimWorld/Config/
• Linux: ~/.config/unity3d/Ludeon Studios/RimWorld by Ludeon Studios/Config/

Sometimes the issue isn't mods at all but a messed-up game installation. If you've installed and removed a lot of mods, especially total overhauls, some data might linger in the core files. This can lead to weird behavior or desyncs that are hard to pin down.

One sign is if you get desyncs even with no mods active (just the base game + MP mod).

RimWorld isn't super demanding, but in multiplayer, if one person's PC or connection can't keep up, it can cause desyncs or at least resyncs where the game tries to catch them up. If you see a message like "X is 2400 ms behind" frequently, that's a red flag.

Inconsistent frame rates can do it too – e.g., a player running at 30 FPS while others run 60 FPS might fall out of sync on complex calculations. The MP mod team notes that running the game below ~30 FPS can lead to connection problems.

Sometimes, you can do "everything right" and still get a desync after a few hours. This tends to happen when you're pushing the game's limits – maybe running a huge 300-mod modpack or managing a sprawling late-game base with 20 colonists and dozens of active events.

The community wryly says if you only desync once every 3-4 hours with 200+ mods, you've got a good setup! The reality is that RimWorld's simulation is deterministic 99.9% of the time – but that 0.1% can bite when you have tons of things happening.

Symptom:

The game desyncs immediately when the world or map is loaded. One player gets in-game, but the other is instantly desynced before unpausing.

Likely Causes:

A mod difference or game version mismatch is most likely. Another possibility is using the "multifaction" feature incorrectly. In rare cases, certain world-generation mods might cause this if not synced.

Fixes:

Double-check the mod situation – even one missing biome mod or outdated patch mod can cause an immediate desync at start. Ensure everyone has the same world seed and scenario settings if you manually set them.

If using Multifaction (competitive or co-op with separate factions), note it's in beta: try starting with the default single-faction first to see if the desync still happens.

Often, an immediate desync is a glaring config or version mismatch – retrace Steps 1–4 of the Quick-Start Fixes. It might sound silly, but confirm that the MP mod itself is enabled for all players.

Symptom:

The game starts fine, but after a random few in-game hours or minutes, a desync occurs. You resync or reload, and then shortly after it happens again.

Likely Causes:

This usually indicates a mod behavior causing divergence. Perhaps an AI routine or a periodic effect that runs differently on each machine.

A classic example: using the "Dubs Bad Hygiene" mod, if the sewage system was enabled, every time the sewage treatment ran, it desynced the game.

Another cause could be the game's random event RNG getting out of sync – e.g., Ideology DLC's rituals were notorious for this around the 1.3->1.4 transition.

Fixes:

Try to observe when the desync happens. If it's during a specific mod's action, consider disabling that mod or feature.

If you suspect a mod like "More Guests" is causing trouble whenever visitors arrive, test by disabling it and see if desyncs stop.

In our ritual example, the solution was to install the Prepatcher tool (the MP mod devs specifically noted that rituals require Prepatcher to sync in MP).

The general strategy: disable one mod at a time (on all sides) and re-test, or start a fresh test game with half the mods to narrow it down.

Symptom:

Only one person drops/desyncs while the other(s) remain fine. For example, the host sees "Player 2 has desynced" but the host is fine and maybe Player 3 is fine.

Likely Causes:

This often points to a problem on the desyncing player's end. Their game files or mod files don't perfectly match, or their PC can't keep up with the simulation causing a timing issue.

Fixes:

First, have that player verify their mod list and versions again. If all looks right, have them use Steam's file verification or reinstall the multiplayer mod.

One trick: Try making the consistently-desyncing player the new host and see if the problem swaps – if suddenly everyone else desyncs, it might indicate that machine has an issue.

Check that the desyncing player doesn't have any local mod adjustments. Sometimes players tweak a mod's files locally, which causes their checksum to differ.

If it's clearly performance-related, consider scaling back the game speed or colony size. That player might lower graphics settings to improve frame rate.

Symptom:

Things were fine early on, but as the colony grew or a massive raid occurred, a desync popped up. Possibly happens when there are 50+ pawns doing things at once.

Likely Causes:

The strain of a large simulation can expose tiny deterministic differences. For instance, lots of gunfire and hits – if a modded weapon uses a random roll that isn't perfectly synced, one client's pawn might hit while another's missed.

More pawns = more chance an unchecked vanilla bug shows. If you have different PC specs, one might struggle when the game state is huge, causing sync issues.

Fixes:

Pause during big events. Let the game catch up, then unpause and proceed step by step.

Make sure to keep everyone's frame rates in sync; if one computer is chugging, the host could use the command /tps 30 to cap tick rate. For comprehensive performance optimization tips, see our RimWorld performance guide.

If mods are involved in combat (like ammo systems), consider disabling those late-game if they prove unstable. Learn more about combat mechanics in our combat and defense guide.

Use the Multiplayer mod's debug info. It has a feature where if a desync happens, it logs a "desync trace" showing what the game was doing on each machine.

Symptom:

You see an error message like "Trace hashes don't match between players" or "wrong random state on map 0".

Meaning:

"Wrong random state" means the random number generator (RNG) on one client got out-of-step. "Trace hashes" not matching means the game's internal state checksums differ.

What to do:

Note what was happening in-game right before the error. If you can reliably reproduce it (say every time a trade caravan leaves), report it to the mod developers with your save file.

Often, if you see these messages, it might correspond to known issues. Ensuring you have the latest mod update is key, because the dev team actively patches these.

For most players, you don't need to dive into the log unless you're curious or seeking help. Just follow the earlier advice: it almost always comes down to something not synced or a mod doing funky things.

Symptom:

Desyncs occur during Ideology rituals, Royalty throne interactions, or Biotech/Anomaly events.

Cause:

Rituals were a known trouble spot. The MP mod team had to implement special handling for them because they trigger complex outcomes and animations.

As of RimWorld 1.5, Ideology rituals require the Prepatcher mod to work properly in MP. The newest expansion Anomaly introduced new mechanics that may not be fully supported yet.

Fixes:

For Ideology – install Prepatcher (available on Steam/GitHub). It's a library that the MP mod uses to patch the game deeper than Harmony allows.

For Royalty – most issues are fixed; just ensure you're up-to-date.

For Biotech – Ensure everyone has Biotech and the MP mod version that supports it.

For Anomaly – If you want stability, you might actually disable the Anomaly DLC for all players when playing MP until the MP mod officially supports it fully.

Symptom:

You and your friend saved the game last night, but when loading up today, you desync within seconds of unpausing.

Likely Cause:

There could be a discrepancy between the save states. Perhaps one of you accidentally continued playing a bit in single-player and then tried to host that save. Or a mod updated overnight and altered something fundamental.

Fixes:

Make sure everyone loads the save fresh, without any differences. Ideally, use the host's save file – in the MP mod, when clients connect, the host's save is sent to them ("Downloading world..." message).

If a mod updated and broke the save's consistency, you have two options: revert the mod to the previous version, or update it on all machines and hope it doesn't break sync.

Another trick: load the save in single-player (with all mods) on the host machine, then use the "Host" button to host it fresh. Sometimes converting the save to SP and back to MP as host cleans whatever was causing an instant desync.

Finally, consider the nuclear option: roll back to an older save that worked.

Date	Update/Patch	Impact on Multiplayer
Oct 18, 2023	Multiplayer Mod v0.9.8 released (for RimWorld 1.4)	Introduced multi-faction support (players can be different factions). Fixed many vanilla desyncs (autosave, quest generation), so starting a fresh 1.4 game on 0.9.8 is much more stable than earlier versions.
Apr 11, 2024	RimWorld 1.5 + "Anomaly" DLC launched	Brought new content (horror events, rituals, etc.) and changes to base mechanics. If you enable Anomaly DLC, some events might not sync – consider turning it off for stable MP. Ensure to use the test version of MP mod (0.10.x) for 1.5.
Jul 16, 2024	Multiplayer Mod v0.10.5 (stable for 1.5)	Finally marked the MP mod as compatible with RimWorld 1.5 (stable). Fixed critical desync sources: hauling to shelves, temperature flickers, pitfall traps, etc. Requires Harmony and Prepatcher if you use Ideology rituals.
Oct 8, 2024	RimWorld 1.5.4241 minor update (birthday patch)	Some bugfixes in base game. After this patch, all players should move to 1.5.4241; it's compatible with MP mod 0.10.5. If someone stays on older 1.5, use Steam beta to align versions.
Apr 9, 2025	PCGamesN Article – "MP mod fully compatible with latest patch"	By this date, it's widely recognized that the MP mod works with all expansions and the current game version. Don't hesitate to start a multiplayer run in 2025 – the earlier hiccups with new DLC are largely resolved.