Civilization 7 Multiplayer Desync and Disconnect on PC

What is the Civilization 7 Multiplayer Desync Error?

The multiplayer desync error in Civilization VII causes all connected players to freeze while the game attempts to resynchronize game states. Players see a "Resynchronizing" or "Out of Sync" message, followed by an automatic reload of the last autosave. In severe cases, the game disconnects players entirely and returns them to the main menu. This is the most common multiplayer issue in Civ 7 and differs fundamentally from single-player crashes — it's caused by game state divergence between the host and clients rather than local hardware or software failures.

When does it occur?

• During Age Transitions, when the game reloads the map with a new ruleset — the #1 trigger
• Every turn in late-game sessions with 6+ civilizations and complex board states
• When one player has mods enabled that other players don't have
• After the host migrates (e.g., original host disconnects and a new player becomes host)
• On turns with heavy combat involving multiple units and simultaneous actions
• When players have significantly different hardware performance causing tick rate mismatches

Common causes

• Age Transition state mismatch: The game regenerates the map during Age Transitions, and clients can calculate terrain or resource placement differently than the host
• Mod version conflicts: Even cosmetic mods can cause desyncs if all players don't have the exact same mod list and versions
• Graphics API mismatch: Players using DX12 while others use Vulkan can experience rendering-related desyncs due to different computation paths
• Network packet loss: Desyncs occur when game state packets are dropped — anything above 1% packet loss triggers frequent resyncs
• Host running in Borderless Windowed mode: This display mode causes frame timing inconsistencies that propagate desyncs to all connected players
• Strategic View rendering bug: Switching to Strategic View mid-turn can cause the client to calculate tile yields differently
• Save file corruption during host migration: When the original host disconnects, the save transfer to the new host can introduce state errors

Step-by-step fixes

1. All players switch to Vulkan — In the game launcher, go to Settings > Graphics > Graphics API and select Vulkan for every player in the lobby. DX12 multiplayer sessions have significantly higher desync rates. This single change resolves desyncs for most players.

1. Host must use Fullscreen mode — The host should switch from Borderless Windowed to Fullscreen Exclusive (Settings > Graphics > Display Mode > Fullscreen). Borderless mode causes frame timing issues that affect all connected clients.

1. Verify identical mod lists — All players must have the exact same mods enabled in the exact same load order. Go to the Mod Manager and compare lists before starting. Disable all mods to test if a specific mod is causing desyncs.

1. Forward Steam networking ports — On your router, forward these ports for the host: TCP 27015-27030 and UDP 27000-27100. Also forward TCP 27036 and UDP 27031-27036 for Steam client communication. This prevents packet loss caused by NAT traversal failures.

1. Use the Age Transition workaround — When a desync occurs during an Age Transition: have one player save the game, all players quit to desktop completely, the host reloads the save and re-hosts, then other players rejoin the lobby. The first turn after reloading may desync once more, but gameplay stabilizes afterward.

1. Let the weakest PC host — Counter-intuitively, the player with the slowest computer should host the game. This prevents the host from processing turns faster than clients can keep up, which is a primary cause of tick rate desyncs.

1. Disable IPv6 on all players' network adapters — Open Network Connections (ncpa.cpl), right-click your active adapter, select Properties, and uncheck "Internet Protocol Version 6 (TCP/IPv6)." IPv6 routing inconsistencies cause packet ordering issues in peer-to-peer sessions.

1. Lower the turn timer and autosave frequency — In lobby settings, enable the turn timer (120 seconds recommended) and set autosave to every turn. More frequent autosaves provide cleaner recovery points when desyncs do occur.

If it still doesn't work

If desyncs persist after all fixes, try using a VPN service with a gaming mode (such as ExitLag or WTFast) to stabilize the connection between players. All players should connect to the same VPN server region to minimize routing differences. Additionally, verify game files through Steam (right-click Civilization VII > Properties > Installed Files > Verify integrity of game files) to ensure no local file corruption is contributing to state mismatches.

For desyncs that occur exclusively during Age Transitions, this is a known engine-level bug that Firaxis has acknowledged on their support portal. Monitor the official Civilization support page at support.civilization.com for patch notes addressing multiplayer stability. In the meantime, saving immediately before each Age Transition and reloading after the desync is the most reliable workaround.