Hello! I've been playing Endless Space 2 for many years without any problems. However, for some time now, I've been unable to play with my son. Every time we launch a game, we get a message saying there are differences in the runtime configuration, with a general reference to the XML files. We can play, but we notice that things quickly become out of sync, ranging from different player colors to critical content that no longer runs in sync. We've had Steam check the files for errors and ultimately even reinstalled the game, to no avail. My son plays on a Windows system, and I play on a MacBook. I've played with many other Windows users in the past, always without problems. Until now. :-(

Can anybody help?

Hello.

I am not a native English speaker, so I will try to help you and explain myself the best as I can.

There is this thread that explains very similar cases to the one you described, maybe you can find some helpful answers. https://community.amplitude-studios.com/amplitude-studios/endless-space-2/forums/73-tech-support/threads/33574-constant-desync-in-multiplayer-every-few-turns-and-xml-discrepancies?page=1 

I don't know if you tried, but if you already tried installing and verifying the game files, try deleting the endless space 2 folder. In windows, the folder is located in "C:\Users\Username\Documents\Endless space 2" and in MacOS in "Username/Library/Application Support/Endless space 2/". 

I would recommend having the game in the same store in both computers. For example, having both games on steam or in gog, etc. Sometimes crossplaying between mac and windows while having the game on different stores can cause some problems.

If this does not work, then be sure to have the same game version installed in both computers. You can check which version you have inside the game main menu, you will see it at the bottom right of the screen. If you have the same version and still does not work, I would try selecting a specific game version. You can specify the game version by going to steam, right-click on the game, and going to properties. Then going to betas, and selecting the version "patchpreview". 

 I hope you find it helpful.​