How to play multiplayer on Linux with Windows players

Company of Heroes 2303 views4 favorites3 min readby Triangular BrickUpdated Sep 7, 2022View on Steam ↗

Introduction

Disclaimer

I'm not responsible of anything that can happen to your devices when you use this guide!

The Facts

So you installed the game with the Linux version and you wanted to try the game out in multiplayer. You try to find an automatch and it's been 15 minutes you've been waiting to play your first match.

People in the community talk about how cool their games were in automatch but yet you didn't find any.
"Why is that?"
Don't worry, the solution is there! Before we apply it though you should understand the problem.

The Problem

After testing things out for you here is the short answer to this Why:

The game's multiplayer mode doesn't seem to be cross platform. Which means:

Linux players are matched with Linux players.
Windows players are matched with Windows players.
It might be the same thing for Mac but I didn't test it. (Do they play with Linux players?)

Conclusion:
Since not much people play on Linux, the player base is much less significant.
The only way to find other players with the Linux version would be to create custom games.

Some of you might think: "Ok let's use Proton then!" (compatibility tool to run Windows games on Linux with Steam)
Well... You'll probably get a sync-error in less than 10 minutes if you play a multiplayer game.

So what do you do to fix this problem?

The Solution

We're going to use a workaround:
Proton... + one file that'll make all the difference in the world!

Let's do it! Up to you if you want to use the terminal or the file explorer!

Uninstall / delete CoH2:
1. Uninstall CoH 2 on steam.
2. Delete remaining files here:
  
  rm -rf ~/.steam/steam/steamapps/common/Company of Heroes 2
3. Delete compatibility data for CoH2
  
  rm -rf ~/.steam/steam/steamapps/compatdata/231430/
Clear download cache
In Steam -> settings -> "downloads" tab
Note: Requires Steam login afterwards. Make sure you know your Steam credentials beforehand!
Reinstall CoH2 on Steam.
Launch CoH 2
At this stage the game would still give 'Sync Error' in multiplayer games either immediately after loading the map or when first enemy is encountered with proton 5.0-10, 5.13-6, 6.3-6, experimental, 6.14-GE-2.

I'm pretty sure you don't need to play a game but just to be safe try doing what I did:
Launch a game in observer mode to watch other people play and quit after 15 minutes.
Download vc_redist.x64.exe
At https://www.microsoft.com/en-us/download/details.aspx?id=48145 from the microsoft website.
Note that another link, namely https://aka.ms/vs/16/release/vc_redist.x64.exe did NOT WORK, as it was missing the required DLL at the time this report was submitted.
Make separate directory to extract vc_redist.x64.exe to.
For example:
mkdir /tmp/vcredist && cp /PATH/TO/DOWNLOAD/vc_redist.x64.exe /tmp/vcredist/vc_redist.x64.exe.
cd to the download directory and extract vc_redist.x64.exe
Using cabextract to the directory you chose as such (Might require a sudo):
cabextract vc_redist.x64.exe -d /tmp/vcredist.

If this did not result in ucrtbase.dll being extracted, use cabextract again to extract the archive file named "a10".
Note: Since I had to extract the archive "a10" and I didn't know the command and I just opened it with the file explorer and the archive manager.
Copy ONLY ucrtbase.dll
To ~/.steam/steam/steamapps/compatdata/231430/pfx/drive_c/windows/system32/
May require sudo privileges.

cp /tmp/vcredist/ucrtbase.dll ~/.steam/steam/steamapps/compatdata/231430/pfx/drive_c/windows/system32/
Launch Company of Heroes 2
In Steam using Proton 5.0-10.
Not yet tested on newer Proton versions, let us know in the comments if it worked!