The Battle.net app installer fails to launch when using PROTON_FSR3_UPGRADE=1

[zefkerr]

Compatibility Report

• Name of the game with compatibility issues: Battle.net app installer.
• Steam AppID of the game: not a Steam app.

System Information

• OS: Arch Linux, GNOME, Wayland.
• GPU: AMD Radeon HD7850 with AMDGPU kernel driver.
• Video driver version: Mesa.
• Kernel version: https://archlinux.org/packages/core/x86_64/linux
• Proton version: https://aur.archlinux.org/packages/proton-cachyos-slr

I confirm:

• [ yes] that I haven't found an existing compatibility report for this game.
• [yes] that I have checked whether there are updates for my system available.
• [ No] that I have verified the issue is present when using Proton-CachyOS-SLR from this repository.
• [yes] that I haven't encountered the issue using an official Proton, such as Proton, Proton Experimental or Proton Bleeding Edge.

• Log from Proton-CachyOS Native (only if relevant)

None

• Log from Proton-CachyOS-SLR

steam-16004681276179087360.log

• Log from recent Proton Experimental

None

Symptoms

The Battle.net app installer fails to launch when using PROTON_FSR3_UPGRADE=1. Works fine without it. When I click the "Play" button, it turns blue forever until I click it again to kill the process, but other than that, nothing happens. What I mean is, the Battle.net app installer doesn't launch. Of course, I understand that no Battle.net game supports any version of the FSR. But I think PROTON_FSR3_UPGRADE=1 should be harmless — meaning, in the worst case, it should do nothing, but it shouldn't make applications and games unable to launch.
https://github.com/user-attachments/assets/70df5628-4917-4063-9346-8401560bf4c2

Reproduction

Set PROTON_FSR3_UPGRADE=1 %command&
Install the Battle.net app in Steam in the fresh prefix.

[loathingKernel]

Works here. The log in your case is empty, meaning that either for some reason your downloading failed or something else unrelated to the fsr3 upgrade option is going on. Try to run Steam from a terminal and see what get printed when you try to launch BNet.

[zefkerr]

@loathingKernel

[loathingKernel]

@Kerrung

This is still normal looking to me, the error just tell you that it is going to be downloaded again.

[zefkerr]

@Kerrung

This is still normal looking to me, the error just tell you that it is going to be downloaded again.

Essentially, the application launch freezes at this point. The application window doesn't appear. This means nothing happens, neither does the application launch nor does the FSR libraries download. Launching it again doesn't change anything, the freeze persists.

[loathingKernel]

@Kerrung

This doesn't mean it is related to the FSR3 upgrade option. All it does at that point is download some dlls from the internet. And if it fails to download them, i.e. there is no internet connectivity, it continues gracefully.

Example output of failing to download it because wifi was turned off

INFO: umu-launcher version 1.2.9 (3.13.7 (main, Sep  9 2025, 16:20:24) [GCC 15.2.1 20250813])
INFO: No GAMEID set, using umu-default
WARNING: Executable not found: winecfg.exe
[Utilities] ERROR: <urlopen error [Errno -2] Name or service not known>
[Utilities] WARN: Failed to download FSR3 dlls.
ProtonFixes[2624635] INFO: Running protonfixes on "cachyos-10.0-20251023-slr-2-g420c2ddc8", build at 2025-10-30 19:46:24+00:00.
ProtonFixes[2624635] INFO: Running checks
ProtonFixes[2624635] INFO: All checks successful
ProtonFixes[2624635] WARN: Game title not found in CSV
ProtonFixes[2624635] INFO: Non-steam game UNKNOWN (umu-default)
ProtonFixes[2624635] INFO: No store specified, using UMU database
ProtonFixes[2624635] INFO: Using global defaults for UNKNOWN (umu-default)
ProtonFixes[2624635] INFO: Non-steam game UNKNOWN (umu-default)
ProtonFixes[2624635] INFO: No store specified, using UMU database
ProtonFixes[2624635] INFO: No global protonfix found for UNKNOWN (umu-default)
Proton: winecfg.exe
Proton: Executable is inside wine prefix, launching normally.
Command exited with status: 0

So figure out what is the problem with your setup and makes it behave like this. Because I cannot reproduce this.

[zefkerr]

BN app also launched and for me too (with PROTON_FSR3_UPGRADE=1) when I turned off Wi-Fi. I previously deleted the cache folder ~/.cache/protonfixes, but that didn't help.