Desync when rejoining long multiplayer game

[lucasdowman]

Hi everyone,

I’ve been playing a long Freeciv multiplayer match (around 6+ hours) with friends, and we noticed something strange when a player disconnects and then rejoins. After reconnecting, their game seems slightly out of sync — for example, unit positions or city production don’t fully match what other players see.
Ragdoll Hit
We’re all using the same version and no mods, and the issue only appears after long sessions.

Is this a known limitation with long-running multiplayer games, or could it be related to server settings (like autosave or turn timeout)? Also, are there any recommended settings or practices to prevent desync when players reconnect mid-game?

[lmn741]

Yes, desyncs after reconnecting in very long multiplayer sessions can happen occasionally, especially on busy servers or with unstable connections. It’s usually not caused by mods if everyone is on the same version.

You could try:

enabling more frequent autosaves
restarting the server occasionally for very long games
increasing turn timeout values
making sure all players have stable latency

Saving and reloading the game on the server can also sometimes fix minor sync issues.

[cazfi]

I’ve been playing a long Freeciv multiplayer match (around 6+ hours) with friends, and we noticed something strange when a player disconnects and then rejoins. After reconnecting, their game seems slightly out of sync — for example, unit positions or city production don’t fully match what other players see.

More likely it's the other player whose client has run out of sync with the server, while the freshly connecting player gets all the correct information from the server anew.

[felixandrea]

Hi everyone,

I’ve been playing a long Freeciv multiplayer match (around 6+ hours) with friends, and we noticed something strange when a player disconnects and then rejoins. After reconnecting, their game seems slightly out of sync — for example, unit positions or city production don’t fully match what other players see.heardle
Ragdoll Hit
We’re all using the same version and no mods, and the issue only appears after long sessions.

Is this a known limitation with long-running multiplayer games, or could it be related to server settings (like autosave or turn timeout)? Also, are there any recommended settings or practices to prevent desync when players reconnect mid-game?

I've seen similar behavior a couple of times in long multiplayer sessions. In my experience it's not usually related to turn timeout settings, but more likely a state synchronization issue that develops over time and only becomes noticeable when a client reconnects and has to rebuild its game state from the server.

A few things I'd try: make sure everyone is on exactly the same Freeciv build (including minor revisions), enable regular autosaves on the server, and have the affected player completely restart their client before rejoining rather than reconnecting immediately. If the problem persists, try loading the latest autosave and see if the desync disappears.

It would also help to know which Freeciv version and server ruleset you're using. If you can reproduce it consistently after several hours of play, it may be worth filing a bug report with save files and server logs, as that sounds more like a synchronization bug than a configuration issue.