Incorrect protocol version
Protocol is not installed on the computer
Verify that the protocol is installed on the computer.
Program reporting the error does not have the same version
Verify that the program you are using or game you are playing is the same version as the program or game that you are connecting. If you are uncertain of the version, update to the latest version of that program or game.
This issue is very common on network games, such as Quake 3, Half-Life, Wolfenstein, and Counter Strike. An error such as Incorrect Protocol Version 66 (the number may vary) indicates the game is not updated to the latest version.
Program reporting the error is running on a different OS
It is common that new operating systems running the same game or code are not compatible. This issue can be often resolved by updating to the latest version of code for that program or game.
Network card does not have the latest drivers
Verify your network card has the latest drivers. For additional information about network card drivers, see our network drivers index.
Protocol is corrupt or bad
If none of the above recommendations resolve your incorrect protocol version issue, reinstall the network protocol.