Fatal Error When Hosting Custom Game

[Thetagent]

Recently I had hosted some Halo CE custom games within the in-game browser, however I can not make it past the pre-game lobby. Once another player joins and the match itself initiates, the game will freeze at the scoreboard and I will receive a popup stating "Fatal Error." Ordinarily I would suspect that this is an issue with me running the game through Proton, however every other game function works without issue. I have not had any trouble with solo campaign, matchmaking, or joining existing custom lobbies. So far I have tried verifying my game files, but that did not work. If anyone could offer up some advice, I would appreciate it.

System Specs:
Kernel: 6.8.2-arch2-1
CPU: Intel i7-10700 (16) @ 4.800GHz
GPU: NVIDIA GeForce RTX 2060 SUPER (Driver Ver. 550.67-3)
Memory: 16 GiB
Proton: GE 9-2

[Nem Dhregin]

Proton is very likely your problem. Since it's not supported, there is very little anyone can do to help you because we can't prove or disprove proton being the issue.

Hosting custom games may invoke different NAT rules, causing the issue as well. There may be a base-windows service that just doesn't exist on your linux machine, so it crashes. but we don't have any documentation for it - so its just a guess. If Proton has a clean-boot option similar to windows, you can see if something is conflicting with MCC when it happens - or if you are aware of your network setup well enough, you can compare it to a normal windows environment.

You can also check the steam deck patch notes for anything useful
https://support.halowaypoint.com/hc/en-us/articles/14589112499348-Halo-The-Master-Chief-Collection-MCC-Steam-Update-April-2023

Primarily, joining groups with people on other OS's causing crashing. No guarantees there, but something to think about.

Lastly, you could submit a bug report to see if there anything official support can offer - though I know its unlikely.