How to Run Firefox on Wayland in Debian Buster

Debian Buster has an option to run Gnome on Wayland (a replacement for X*). As indeed did Stretch, but in Buster, it's possibly going to be the default.

I had assumed that, if I selected Wayland, all applications would use it, but apparently not. Applications that can't use Wayland can use a compatibility layer called XWayland.

It seems Firefox has had Wayland support since version 65, but the default is still for the program to use XWayland.

Debian Buster of course has ESR 60 at the time of writing, but I have been trying out Firefox downloaded from the Mozilla website from my /home directory, and that is currently at version 67. (That's to say, downloaded from Mozilla, to my /home directory, and run from there, if the previous sentence didn't make sense.)

Thanks to a post on the Debian User Forums, I discovered I could launch Firefox on Wayland using this command:

$ MOZ_ENABLE_WAYLAND=1 ~/Downloads/firefox-67.0/firefox/firefox

Of course, if you have unpacked Firefox to a different location, use that location.

Firefox runs (with some weird error messages in the terminal:

IPDL protocol Error: Received an invalid file descriptor ###!!! [Child][RunMessage] Error: Channel closing: too late to send/recv, messages will be lost

But is it running on Wayland?

I found a suggestion to use Xeyes because, being based on X, Xeyes won't work on Wayland Windows. Indeed, the eyes follow the mouse cursor in the Firefox window when launched normally, but not with Wayland enabled.

*What do you mean, that doesn't explain anything? Well, if you want the full explanation of what Wayland is, it's here.