White screen on SteamOS Linux (Game mode)

[mistrk7]

Describe the bug

After adding the Modrinth launcher as a non-steam game, launching it in Game mode only displays a white screen.

Steps to reproduce

1. Go into Desktop mode
2. Install Modrinth AppImage
3. Right click it > Add as a non-steam game (navigate to the file)
4. Go back into Game mode
5. Launch the non-steam game

Expected behavior

The Modrinth UI should display and work as expected.

Additional context

Note that this is not a crash.

I can still move the mouse, and it changes on where interactable elements would be. Can also exit out the application fine.

I suspect it could have something to do with the Wayland window system protocol. Desktop mode still uses X11 which is the old standard and it works fine there.

[llakala]

Confirming this, having the same issue on my Steam Deck

[Chaphasilor]

Can confirm that just the displaying is the culprit, I managed to guess the position of the "jump back in" button for a profile and minecraft booted up just fine (and displayed normally)

[xdinterface]

Can anyone check if this this might fix the issue?

There is a WebKitGTK bug that might be causing this.

EDIT: I am pretty sure adding WEBKIT_DISABLE_COMPOSITING_MODE: 1 will solve the issue.

[mistrk7]

Can anyone check if this this might fix the issue?

There is a WebKitGTK bug that might be causing this.

EDIT:

I am pretty sure adding WEBKIT_DISABLE_COMPOSITING_MODE: 1 will solve the issue.

success! Got it to work by changing the Target command to:

env WEBKIT_DISABLE_COMPOSITING_MODE=1 /directory/to/appimage

Thanks.

[Routhinator]

This isn't exclusive to Steam OS - it's a general flatpak issue that should be fixed.

I'm here because I have the exact same behavior OOtB with Kubuntu 23.10.

I had to modify the Flatpak with Flatseal to add the env var.

This flatpak should be shipping with this env var set by default to fix it for all platforms.

[brawaru]

@Routhinator Flatpak for Modrinth App is not maintained by Modrinth. Please report issues with Flatpak version to https://github.com/flathub/com.modrinth.ModrinthApp/issues. I'm sure they'll be open to fix this if this is just a one variable change 👍

[Awakened-Redstone]

@Routhinator not necessarily a flatpack issue, I installed it trough AppImage and the AUR on arch and I also have this issue

[ShawZam]

this is most definitely not just a flatpak issue, ive tried all the install methods on Ubuntu 24.04 and i get this issue. Seems to be an issue related to graphics drivers if the info I've googled is correct. when launched from terminal i get this : WARNING **: 01:43:12.978: webkit_settings_set_enable_offline_web_application_cache is deprecated and does nothing. Gtk-Message: 01:43:13.038: Failed to load module "canberra-gtk-module" . It persists until I launch using "export WEBKIT_DISABLE_DMABUF_RENDERER=1"

[Geometrically]

Can you try running the Modrinth App with this env var set? It should fix the issue:

WEBKIT_DISABLE_COMPOSITING_MODE=1

See here: https://github.com/tauri-apps/tauri/issues/5143#issuecomment-1374040005

[ShawZam]

adding variable to flatseal made Modrinth work! Thanks!

[41exio]

I was having no issues launching Modrinth as a non-steam game with 0.7.1 (main Linux download, not flatpack version), but came here after upgrading to 0.8.2. The WebKit fix worked though!

Reproduction steps:

1. Download default Linux AppImage from https://modrinth.com/app.
2. Add non-steam game, browsing to path of where AppImage was downloaded.
3. Under properties, set "Launch Options" to: WEBKIT_DISABLE_COMPOSITING_MODE=1 %command%
4. Launch Modrinth

The Modrinth app interface isn't easy to navigate (easier to use in Desktop mode) but well enough to mash the touch screen with my fat fingers to then launch a profile.