Hello @Milli189, please add PROTON_LOG=1 %command% to a couple game's launch options and attach the generated $HOME/steam-$APPID.log to this issue report as a file. (Proton logs compress well if needed.)

One-armed robber log:

steam-2551020.log

The Tartarus Key log:

steam-1431850.log

I think I can't because the Kisak-Mesa PPA doesen't support ubuntu 25.04, and I don't know of other ways to update it

I'm seeing something similar with (1407200) after a recent Proton Experimental update on Debian Bookworm (with stable-backports, stable-proposed.) No access to mesa 25.1.* as yet. I can switch to Proton 9.0 okay I think.

I am pretty sure this is what was causing nearly all of my proton games to fail to launch on Ubuntu 22.04. I get the same popup in the screenshot with the error text as above. I am running on a 13th gen intel with integrated graphics. After installing the latest mesa from the kisak ppa it launches under proton experimental, but is incredibly glitchy. It seems to hold on to old frames and randomly interleave them or something, super odd behavior that is not present on proton 9.

The error messages from the games are usually some variation on this:

Failed to initialize player
Failed to initialize graphics.
Make sure you have DirectX 11 installed, have up to date
drivers for your graphics card and have not disabled
3D acceleration in display settings.
InitializeEngineGraphics failed

PROTON_LOG=1 revealed this (before updating mesa beyond what is available in ubuntu's own repos):

err:   D3D11InternalCreateDevice: Failed to create D3D11 device
warn:  CreateDXGIFactory2: Ignoring flags
info:  Intel(R) Graphics (RPL-P):
info:    Driver : Intel open-source Mesa driver 23.2.1
info:    Memory Heap[0]: 
info:      Size: 48008 MiB
info:      Flags: 0x1
info:      Memory Type[0]: Property Flags = 0x1
info:      Memory Type[1]: Property Flags = 0x7
info:      Memory Type[2]: Property Flags = 0xf
info:  D3D11InternalCreateDevice: Maximum supported feature level: D3D_FEATURE_LEVEL_11_1
info:  D3D11InternalCreateDevice: Using feature level D3D_FEATURE_LEVEL_11_1
info:  Required Vulkan extension VK_KHR_maintenance5 not supported

I have the same error using Proton Experimental/Hotfix. Proton 9.0-4 works fine.

My OS is Debian 12 with mesa 22.3.6-1+deb12u1.

err:   D3D11InternalCreateDevice: Failed to create D3D11 device
warn:  D3D11CreateDevice: Unsupported driver type
info:  AMD Radeon R9 390 Series (RADV HAWAII):
info:    Driver : radv 22.3.6
info:    Memory Heap[0]: 
info:      Size: 7936 MiB
info:      Flags: 0x1
info:      Memory Type[0]: Property Flags = 0x1
info:      Memory Type[1]: Property Flags = 0x1
info:    Memory Heap[1]: 
info:      Size: 7973 MiB
info:      Flags: 0x0
info:      Memory Type[2]: Property Flags = 0x6
info:      Memory Type[4]: Property Flags = 0xe
info:    Memory Heap[2]: 
info:      Size: 256 MiB
info:      Flags: 0x1
info:      Memory Type[3]: Property Flags = 0x7
info:  D3D11InternalCreateDevice: Maximum supported feature level: D3D_FEATURE_LEVEL_11_1
info:  D3D11InternalCreateDevice: Using feature level D3D_FEATURE_LEVEL_11_1
info:  Required Vulkan extension VK_KHR_maintenance5 not supported

I belive I'm having the same issue, several modern games do not launch at all, on Iris XE, fedora 42,
the problem seems to cover mostly unity games like mechabellum and xenonauts 2(which runs fine if I launch it manually)