OpenRCT2 Server Version Mismatch and Desync Fixes

Most OpenRCT2 multiplayer problems come down to versions. Incorrect Software Version (Server is using ...) means the player's OpenRCT2 build differs from the server's, and the fix is to install exactly the version shown in the message, or move the server to the version your group runs. Network desync detected means a player's copy of the park drifted from the server's, usually from a mismatched build, a plugin or a flaky connection, and reconnecting resyncs it. The rest, from bad passwords to "Unable to advertise", have one clear cause each, listed below.

Why OpenRCT2 is so strict about versions

OpenRCT2 multiplayer is lockstep: the server sends player actions, and every client simulates the park itself. For that to work, every copy of the game must do exactly the same maths on every tick. Any change to the game code, even a small bug fix between two development builds, can change the outcome. So the server compares a network version on join and refuses anyone who does not match exactly. Release builds and development builds with the same number on top are not the same thing.

"Incorrect Software Version (Server is using ...)"

The text in brackets is the server's version. Fix it from either side:

Match the player to the server. Download the same release from the OpenRCT2 releases page and install it. If the server runs a development build, the player needs the same development build, not the release with a similar number.

Match the server to the players. If the whole group has updated, update the server. Install the same release on the server, then restart it with your park.

Things that cause surprise mismatches:

• Auto updates on one side. A launcher or package manager quietly updated someone's client after the server was set up. Agree on a version and pin it.
• Develop builds. One person runs a nightly "develop" build for a new feature. Develop builds change constantly, so pick releases for group play.
• Different platforms are fine. Windows, macOS and Linux players can play together as long as the version matches exactly.

"Network desync detected"

A desync means a client's park no longer matches the server's: a guest is somewhere else, a ride has a different state, or money differs. The client notices and shows the message, and the player can reconnect, which downloads a fresh copy of the park from the server.

If one park keeps desyncing for everyone, turn on desync_debugging = true under [network] in the server's config.ini. The game then writes desync_*.txt reports into the user data folder that show what differed, which is what the OpenRCT2 developers ask for in bug reports. Turn it off again afterwards, since it costs performance.

"Bad Password"

The password does not match default_password in the server's config.ini. Passwords are case sensitive. Admins and anyone in a group with the passwordless login permission skip the password, which is why the person who set it up may never notice it is wrong.

"Server Full"

The server has reached maxplayers in config.ini, 16 by default. Raise it and restart, or have idle players leave.

"This server only allows whitelisted players to connect."

known_keys_only = true is set, and the player's key hash is not in users.json. Either add them, set their group once while the whitelist is off so the server saves their hash, or turn known_keys_only off. How hashes work is covered in how to make yourself admin on an OpenRCT2 server.

Joins but cannot build

Not an error, but the most common complaint. New players join the Spectator group, which can only chat. An admin sets the default group to User on the Groups tab of the Multiplayer window, or promotes players one by one.

"Connection Closed" or nothing happens

The player cannot reach the server at all:

1. Check the server is running and the console showed Listening for clients on *:11753 (or your port).
2. OpenRCT2 uses TCP. A router rule for UDP only will not work. Forward TCP 11753 and allow it in the firewall. See how to port forward a game server.
3. Check the player typed the right port. If you changed default_port, they need address:port.

Not in the server list: "Unable to advertise"

With advertise = true, the server registers with the OpenRCT2 master server and the console says Server successfully registered on master server. If it says:

Unable to advertise (...): ...
  * Check that you have port forwarded 11753
  * Try setting advertise_address in config.ini

the master server could not reach your port from outside. Fix the port forward first. If the server machine has several addresses, or the master picks up the wrong one, set advertise_address under [network] to your public IP. Players on the same LAN find the server without the master, through UDP broadcast on port 11754.

A private group does not need the list at all: set advertise = false and have everyone use Add Server with the address.

On a GamezServers server

A GamezServers OpenRCT2 server has an OpenRCT2 Version setting in the panel. Set it to the exact release your group has installed, for example a v0.4 or v0.5 tag from GitHub, or leave it on latest and keep everyone updated, so the server runs the same build as your players. The panel also covers the password, max players, advertising, pausing when empty and loading the latest autosave, and config.ini is in the file manager for desync_debugging and known_keys_only. Take a one click backup before changing versions so you can roll back if the park needs an older build. New to hosting? Start with how to host an OpenRCT2 server.

FAQ

Why does OpenRCT2 say incorrect software version?

The player's OpenRCT2 build is not identical to the server's. Install the exact version shown in brackets in the message, or update the server to match the players.

Can Windows and Mac players play OpenRCT2 together?

Yes. Platform does not matter, only the exact OpenRCT2 version does.

How do I fix OpenRCT2 desync?

Reconnect to resync the park. If it keeps happening, make sure every player runs the same build as the server and remove plugins that change the park on one side only.

What port does OpenRCT2 multiplayer use?

TCP 11753 by default. LAN discovery uses UDP 11754.