protonscr

Loadout

protonopen appid 208090Game compatibility - UnofficialRegression
ValveSoftware/Proton#10166 · opened 2026-09-22 by voltflake · updated 2026-09-24 · 4 comments · github · game page · search this game
Vvoltflake 2026-09-22 github

Compatibility Report

  • Name of the game with compatibility issues: Loadout
  • Steam AppID of the game: 208090

System Information

  • GPU: NVIDIA / AMD / Intel
  • Video driver version: Any
  • Kernel version: Linux 6.x
  • Proton version: Proton >= 11.0 (Broken) / Proton <= 10.0-4 (Working)

I confirm:

  • [x] That I haven't found an existing issue for this game in the issue tracker (or that my issue is a newly introduced regression in Proton 11).
  • [x] That I have checked whether there are updates for my system available.

Symptoms

Starting Loadout under Proton 11 or newer results in an immediate crash during early initialization (shortly after the splash screen appears, before the main menu loads). The game launcher terminates with an Access Violation (0xC0000005) and spawns SubmitReport.exe.

  • Proton 10.0-4: Works out of the box.
  • Proton 11.0: Crashes during RenderSystem init.

Reproduction Steps

  1. Install Loadout (Steam AppID 208090).
  2. Force Compatibility tool to Proton 11.0 or newer.
  3. Launch the game -> Game closes within 2–5 seconds with crash reporter window popping up.
  4. Switch Compatibility tool to Proton 10.0-4 -> Game boots successfully to server connection screen.

Relevant Log Excerpt

Game crash report shows:

...
Loadout.exe has encountered an unrecoverable error: 
Error Type: Access violation
...
Vvoltflake 2026-09-22 github
Game works as intended on Proton 10, 9, 8, 7 but crashes at startup on 11 and newer ones. If game files needed for testing/reproduction, tell me and I'll send files and instructions on how to set it up. When I was investigating with help of ai agent i was able to identify more precisely where issue is.

Key Commits in Proton's Tree

When testing downstream Wine patches on top of upstream Wine:

  • Upstream wine-10.0 (b0738596750) alone: Crashes.
  • Upstream wine-11.0 (db11d0fe6a1) alone: Crashes.
  • The game requires Proton's downstream Large Address Aware override to boot.

In Proton 10's development history:

  • 8e9c69c02866a95ead4dd87f28cb52a1e75d0e91 -> CRASHED
  • 3440612b763bbe88b4561c4e6aa426e10774dff3 (fixup! ntdll/loader: add support for overriding IMAGE_FILE_LARGE_ADDRESS_AWARE) -> BOOTED CLEANLY
    • This commit replaced __wine_needs_override_large_address_aware with __wine_get_unix_env() via Unix call thunk and made sure virtual_set_large_address_space() and free_reserved_memory((char *)0x80000000, address_space_limit) actually unreserved memory on 32-bit i386-unix.

In Proton 11 (proton_11.0 branch):

  • Downstream rebase commit 799e5f0f562335907853021bd6bfbfe0900f2fb7 (ntdll/loader: add support for overriding IMAGE_FILE_LARGE_ADDRESS_AWARE) and current HEAD dc26e618470:
    • Native 32-bit i386-unix build of ntdll.so crashes during Themida unpacking.
    • Themida creates a section view for integrity verification, unmaps it (NtUnmapViewOfSection), and allocates right into that range; the memory mapping/limits fail to accommodate the unpacker, causing an immediate 0xC0000005 Access Violation.
Kkisak-valve maintainer 2026-09-22 github

Hello @voltflake, this is a lot of noise for what could have been written as: "The game needs PROTON_FORCE_LARGE_ADDRESS_AWARE=0 %command% to start with Proton 11."

Please add PROTON_LOG=1 %command% to the game's launch options, reproduce the crash, and attach the generated $HOME/steam-$APPID.log to this issue report as a file. (Proton logs compress well if needed.)

Vvoltflake 2026-09-22 github

@kisak-valve thanks for suggestion but unfortunately that doesn't fix anything. Attached proton log and game crash report.

loadout_proton11_crash_report.zip

steam-208090.log

Vvoltflake 2026-09-24 github

@kisak-valve sorry for providing my early investigation details, they were flawed. I did my "homework" now and i managed to make a minimal fix locally. Regression was caused by new compiler standards introduced in GCC 14.2 which is shipped by SteamRT 4 (Medic) SDK, previous environment used GCC 10. Starting from GCC 12, -ftree-vectorize optimization became included into -O2 flag. This optimization caused something in user32.dll to misbehave in a way that made game crash with access violation. Adding -fno-tree-vectorize when compiling user32.dll causes game under resulting proton build to no longer crash. Should i open an issue about that in proton-wine or leave my investigations here? I'd really like to speedup fix development and i don't really know what is the best way to do it here...

Kkisak-valve maintainer 2026-09-24 github

In general, we're using one issue report per game title. This is the right place for all feedback related to this game.

Related threads

Proton versions

Launch options

Launch lines

DLLs

Error codes