This is a Proton issue, not a vkd3d-proton issue; Forza Horizon 4/5 spawns two windows in fullscreen with the black window often spawning on top of the actual game window. This was worked around in previous Proton versions but Proton 11's (and by extension, Experimental's) rebase seems to have brought this issue back.
Running in Windowed mode also eliminates this issue as only one window spawns.
This is a Proton issue, not a vkd3d-proton issue; Forza Horizon 4/5 spawns two windows in fullscreen with the black window often spawning on top of the actual game window. This was worked around in previous Proton versions but Proton 11's (and by extension, Experimental's) rebase seems to have brought this issue back.
Running in Windowed mode also eliminates this issue as only one window spawns.
Running it in windowed mode solves the problem, but the image looks like when you try to enlarge a small photo; it looks blurry as if it were at low resolution. Maybe on 1080p screens it's not so noticeable, but at 1440p or 4k it looks bad.
I'm running Arch with KDE and am experiencing this issue. A work-around that I found was to set the game to fullscreen and open another non-fullscreen window (with alt-tab; the start menu and command pallete, alt+enter, also work) over the top. The black window should disappear, just click on the game behind the window you opened (alt-tab doesn't work) to switch focus to it.
proton experimentalx1 2026-05proton hotfixx1 2026-05gamescope -- %command%x1 2026-05
Everything was been working fine until I upgraded from Proton experimental-11.0-20260428 to Proton experimental-11.0-20260507 and then I will tried with proton-hotfix, but the problem persisted. For now, proton-11-beta is working.
Suddenly, Forza Horizon 4 & Forza Horizon 5 started having issues. When launching it through a gamescope-session or from the desktop using gamescope -- %command%, the game appears to start correctly: I can hear audio, and inputs from the controller, keyboard, and mouse seem to register. However, the screen remains completely black, forcing me to switch from fullscreen to windowed mode by pressing Alt and then Enter, the game displays correctly, although at a slightly lower resolution. From what I've found in forums, this problem occurred a couple of years ago, but it had been fixed, until now.. It seems that fix was overwritten in the latest version of Proton-experimental.
#Affected game(s)
Forza Horizon 4
#App ID
1293830
Forza Horizon 5
#App ID
1551360
#System specs:
CPU: Intel i9-10900K
RAM: 64 GB
GPU: AMD RX 5700 XT
Bazzite 43 Plasma 6 - CachyOS Plasma 6- Arch linux Plasma 6 (I was able to replicate the error on all three of my computers)
forza-4-steam-1293830.zip
forza-5-steam-1551360.zip