Desync in Gaming: What It Is and What Causes It
Desync, short for desynchronization, means that two parts of a multiplayer game no longer agree about what is happening. Usually that is your game client against the server, sometimes two clients against each other. You see an enemy in one place and the server counts them in another, or the game stops with an "out of sync" message.
The word covers two quite different problems, and the usual advice ("get a better connection") only fits one of them. This page uses examples from Source-engine shooters, Factorio and Escape from Tarkov (version 1.3.0, October 2026), checked on 2 November 2026.
Two kinds of desync
| Server-authoritative games | Lockstep games | |
|---|---|---|
| How state is shared | The server holds the true state and sends snapshots; your client predicts in between | Only player inputs are sent; every machine simulates the whole game itself |
| Typical genres | Shooters, MMOs, battle royale | Strategy games, factory builders such as Factorio |
| What desync looks like | Rubberbanding, hits that do not count, dying after reaching cover | A disconnect or "out of sync" screen |
| Does a bad connection cause it? | It makes mismatches larger and more visible | No. Factorio's wiki states that network, latency and performance problems do not cause desyncs |
| Usual real cause | Prediction and lag-compensation limits, server bugs | A code bug, a mod or scenario bug, or a calculation difference on one machine |
How a shooter desync happens
Valve's developer documentation for the Source engine describes the mechanism with a 150 ms example (Counter-Strike 2 runs on Source 2, which the same page lists at 64 ticks with sub-tick updates). You press forward; the command travels to the server, and the confirmation comes back 150 ms later. To hide that delay, your client predicts the result of your own input and moves you instantly. When the server snapshot arrives, the client compares it with its prediction. If they differ, a prediction error has occurred, and your character is pulled to the position the server says is right. That visible correction is what players call rubberbanding.
Other players are shown with a built-in delay. Source games draw them about 100 ms in the past by default (cl_interp 0.1), so there are always two snapshots to blend between. If more than one snapshot in a row is lost, the client extrapolates movement for up to 0.25 seconds and then gives up, because the errors grow too large.
Shots are judged by lag compensation: the server moves other players' hitboxes back in time to where you saw them. Valve's own page admits the side effect: you can be hit by someone you can no longer see, because the server rewound your hitbox to a moment when you were still exposed.
Desync in real games
| Game | What desync means there | Documented detail |
|---|---|---|
| Source-engine games | Prediction errors, hits after taking cover | cl_showerror 1 shows prediction errors; Valve says this inconsistency cannot be solved in general |
| Factorio | The client disconnects and downloads files to build a desync report | The report holds your copy and the server's copy of the save; when mods are installed they are usually the cause; restarting the server can work around it short term |
| Escape from Tarkov | Positions, grenades or doors differ between client and server | 6 July 2023 (0.13.1.0): netcode rework "reduced the chance of desync" and improved position matching. 10 February 2026 (1.0.2.0): grenade-throw synchronization improved to reduce grenade position desync. 6 October 2026 (1.2.0): server-side position sync improved to cut rubberbanding, with more work promised |
Notice that Tarkov's developers still list synchronization work in 2026. Desync is reduced by patches, not removed.
Desync, lag and rubberbanding
- Lag is delay between your input and the result. It is a symptom of latency.
- Rubberbanding is the visible snap back when the server overrules your client. It is one symptom of a server-authoritative desync.
- Desync is the underlying disagreement. You can have it with a low ping if the game's prediction or server code gets something wrong.
In Source games, net_graph 2 (or +graph) draws a live graph of connection speed and quality, which helps you see whether packets are really arriving late or missing.
What you can do
- In a server-authoritative game, choose the nearest server region and use a wired connection. This can reduce the gap the prediction has to bridge, though it cannot fix a server-side bug.
- If hits feel wrong, check how your game's hit marker feedback is defined before blaming desync, and look for the cover paradox described above.
- In a lockstep game, remove mods first, rejoin, and restart the host server. Factorio's wiki warns that a restart may not work and players can still desync on rejoining.
- Keep the game updated. Fixes for synchronization arrive in patches.
- When reporting a bug, note the time, map or location and what you saw. Developers cannot act on "desync" alone.
Related terms
- Server region: where the machine that judges your game sits.
- Hit marker: the feedback that may or may not wait for the server.
- Escape from Tarkov wiki: more Tarkov terms, including network ones.
- General gaming terms: the rest of the game-neutral glossary.
FAQ
Is desync the same as lag?
No. Lag is delay; desync is a disagreement between client and server about what happened. Lag can make desync more visible, but a desync can happen at low ping, and Factorio's lockstep multiplayer does not desync from lag at all.
Why did I die after I got behind cover?
Most likely lag compensation. The server judged the shot against your position as it was when the shooter fired, so you were still exposed there. Valve describes this exact case in its Source networking documentation.
Can packet loss cause desync?
In server-authoritative games, lost packets force the client to guess, and bigger guesses mean bigger corrections. In lockstep games the network layer handles loss, and desyncs there point to a bug or mismatched calculation.
Can I fix desync on my side?
Only partly. A stable wired connection and the right region reduce prediction errors, and removing mods helps in lockstep games. If the cause is server code, only a developer patch fixes it.
