GUI fails to load on Linux

[nwagenbrenner]

The GUI fails to load with error:

GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.

I'm using the master branch and Qt version 6.10.1 This may the be same issue that @latwood is seeing.

Searching online, this apparently happens on Linux systems when the Generic Buffer Management (GBM) backend—used for sharing graphics buffers between applications—cannot be initialized. This is a common behavior in recent versions of Qt WebEngine (based on Chromium) and standalone Chromium browsers, especially when running on NVIDIA hardware.

This can happen because:

• NVIDIA Compatibility: NVIDIA's proprietary drivers historically lacked full GBM support or required specific configurations to work with Wayland.

• Qt WebEngine Behavior: In newer versions (e.g., Qt 6.9+), Qt WebEngine attempts to use GBM to import textures. If it fails, it forces Chromium to use Vulkan as a fallback to maintain graphics interoperability.

• Compositor Issues: The error can occur if you are running a window manager without a compositor or using an environment that doesn't support the specific rendering path the browser is requesting.

Potential Fixes and Workarounds:

• If the fallback causes performance issues, crashes, or visual glitches (like black screens), you can try the following:

• Disable GPU Acceleration: For some applications (like CoolerControl), launching with the --disable-gpu flag can bypass the rendering error.

• Force Disable GBM: Set the environment variable QTWEBENGINE_FORCE_USE_GBM=0 before launching the application.

• Switch Ozone Platform: If running on Wayland, try forcing the application to use X11 via XWayland with the flag --ozone-platform=x11.

• Software Rendering: If Vulkan and GBM both fail, you can force software rendering using --use-gl=disabled or -s qt.force_software_rendering.

• Check Drivers: Ensure you have the latest drivers installed. For NVIDIA, verify you have packages like nvidia-utils and lib32-nvidia-utils (on Arch-based systems) or equivalent libraries for Vulkan support.

• Diagnostic Tool: Visit chrome://gpu in your browser to view the "Graphics Feature Status" and "Dawn Info" to see exactly which components are failing to initialize

[nwagenbrenner]

I think the GUI is actually failing to load due to a license check issue and is unrelated to the warning message mentioned above. Looking closer in the compile output when I build the GUI code, I see this:

AutoMoc: Could not request license for qtframework:
Message: No valid license could be acquired. Please contact your license admin. For more details, see: https://doc.qt.io/qtlicenseserver/qls-reference-troubleshooting-service.html#qt-license-service-error-messages.
Status code: 100
Error details:
• The licenses available to the current user have expired. License IDs:
11802716. Check your available licenses in the customer portal or
contact your local license admin. For more details, see
https://doc.qt.io/qtlicenseserver/qls-reference-troubleshooting-server.html#reservation-errors.
Cannot acquire license to use qtframework.

If you have a valid commercial license, please create a bug report to Qt Bugtracker:
https://bugreports.qt.io/projects/QLS

Attach the above details to the bug report.

My Qt install must have been associated with a trial commercial license that expired. I'll have to try reinstalling Qt and ensure that I choose the open source option (or whatever needs to be done to specify that). We'll need to make sure we clarify this in our Linux build instructions. Ideally, we could automate this all for the user so they don't have to manually get and install Qt. The best would be if we could automate this in our build script.

[nwagenbrenner]

I've reinstalled Qt ensuring it's using the open source license. I no longer see the license or any other warnings when compiling, but the GUI still does not load when I fire the executable. I get the phone home pop up box but nothing happens after I dismiss that. I'm not sure what's going on. I'm using Qt 6.10.3.

[nwagenbrenner]

Additional debugging suggested a test of

~/Qt/6.10.3/gcc_64/libexec/QtWebEngineProcess --help

This produces a seg fault for me. Additional reading indicates this may be a mismatch between some of my system components and webengine.

A segmentation fault in QtWebEngineProcess even with software rendering and --help strongly suggests a low-level environment incompatibility, likely related to accessibility loops or resource-sharing deadlocks introduced in the Qt 6.10 series.