How I fixed it: Firefox crash on Hyprland

Background

As a developer, when something crashes on my computer I’m inclined to fix it. Obviously that comes with the trade of writing your own software, but we are also empowered with the knowledge and skill to find ways to contribute to fixing issues in programs and apps we didn’t write ourselves.

In the world of open source we even have the superpower of modifying programs someone else wrote, then build and run it without ever involving the upstream maintainers. This is obviously great, but also cursed, in a way. Knowing you are able to fix something can be frustrating when you feel you don’t have the time or energy to do so.

I will admit as I’m getting older my threshold for debugging issues in other people’s software is getting higher. Lazy, I know. But when I experience weird crashes in off the shelf applications I quickly turn to search engines to see if someone else has experienced similar issues.

Before LLMs we relied on people to continously publish their issues and solutions online for this to work. Now this has obviously changed quite significantly. LLMs provide great help just for you in your particular situation, but the rest of the world won’t see a trace of this interaction (besides the model providers, of course.)

So I thought to get back into writing I’d take some of the issues I experience and try to document how I fixed them (or abandoned trying.)

The crash

I choose to use Firefox as my main browser and have been happy with it for the last decade or so. One prerequisite for me to use a piece of software however, is that it works™.

For the last few weeks I’ve noticed that both Firefox and Thunderbird has been crashing when I leave work with my laptop. It happens the second I unplug the USB-C cable connecting two external displays and a keyboard and presents the following error:

Crash Annotation GraphicsCriticalError: |[0][GFX1-]: (hyprland) Wayland protocol error: wp_color_manager_v1#46: error -1: Invalid output (2)
(t=3.49975) [GFX1-]: (hyprland) Wayland protocol error: wp_color_manager_v1#46: error -1: Invalid output (2)

I’m not going to admit to how long I kept up with just restarting Firefox (and had to unlock my password manager browser extension with a stupidly long password.) But eventually I couldn’t take it any longer.

First I seriously considered switching to Chromium just because of my laziness. But it didn’t even take an hour before I realized I didn’t really enjoy that experience.

Time to scour the internet for solutions!

The bug report

Turns out there’s already an upstream issue reported on Bugzilla, Firefox’s issue tracker.

The report states that Firefox crashes on Wayland upon losing a display. Sound like we got it!

Looking closer at the issue could be a generic Wayland and Firefox issue, but the only reports that I’ve found mention Hyperland (my window manager.) To resolve this issue let’s see if there are any issues or fixes for Hyperland in particular.

And there is!

https://github.com/hyprwm/Hyprland/pull/11916

The fix

When there are bugs in software that you use and you don’t build everything yourself from source, you’re by default at the mercy of package maintainers to get fixes into upstream packages.

The same applies for the default experience on NixOS. However, since packages (or derivations) on NixOS basically are defined through their build recipe it’s trivial (once you know how) to patch software yourself.

The fix for Hyprland#11916 is already merged and applied in main upstream, but there hasn’t been a release containing it yet. Regardless, we can quite easily replace the source of the hyprland package in a NixOS configuration by specifying an overlay pulling down a source tree containing the fix.

From my personal NixOS configuration in myme/dotfiles:

# overlay.nix
{
  hyprland = nixpkgs.legacyPackages.${prev.system}.hyprland.overrideAttrs ({
    version = "0.51.1-patched";
    src = prev.fetchFromGitHub {
      owner = "hyprwm";
      repo = "hyprland";
      fetchSubmodules = true;
      rev = "ab11af9664a80df70fe3398810b79c4298312a33";
      hash = "sha256-dSAPRyKzxM+JodX5xBCmpVrVYWjYpNPPiSySaI4W+rQ=";
    };
  });
}

Hydra builds packages in the maintained NixOS release channels, but once we create an overlay we generally won’t find existing builds. What nix does when applying the configuration is that it doesn’t find a cached derivation and proceeds to build it on the spot.

After a nixos-rebuild switch --flake .# I now have a laptop setup where Firefox no longer crashes when I unplug USB-C cables connected to external displays. Great success!

Once the fix to makes it into the next NixOS stable release I can remove the overlay and use the stock package.