Firefox crashes unity8 zesty

[kevin gunn]

I believe this is a different bug than bug 1627311

using a fresh zesty install, logging into unity8 deb session
I installed libertine manager
Since FF is installed as part of the original image - it shows up automagically in the app drawer.
Clicking on the icon, a unity8 app window with a splash appears, but eventually fails.

The only real error i see is in ~/.cache/upstart/application-legacy-firefox-blah.log
 Error: GDK_BACKEND does not match available displays

[kevin gunn (kgunn72)]

adding xorg in case it's related to xmir

[Christopher Townsend (townsend)]

Ok, I looked a bit, and it appears Firefox is trying to use the GDK-Mir backend, but I'm guessing the GDK-Mir backend is not mature enough yet (?), so the app bails.

Definitely not an Xmir issue as Xmir is not even trying to be used in this case.

[William Hua (attente)]

There's some platform-specific code in firefox itself that's trying to detect the display name using the environment, but it's only been done for x11, wayland, and broadway. It needs to be fixed in upstream firefox:

https://hg.mozilla.org/mozilla-central/file/f7e1982a2582/toolkit/xre/nsAppRunner.cpp#l2896