I did a clean install of KDE Neon this week and I noticed Firefox is not really set as default. When I go in system settings I see it is set. When I open a .html file or click on a link, it opens Firefox.

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But when I go in Firefox preferences, it is not detected as default:

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Additionally, I cannot open my Firefox Bookmark with Krunner (which is very annoying), but I think the two problems are related.

How could I fix this issue?


It's something with an environment variable:

I have the same problem and it seems an issue with KDE itself. I've found that the whole problem is related to the following environment variable:


To fix:

As we all known, KDE works on QT and it's probable something with GTK on Firefox. To fix the issue, one must edit the following file:


And on the first Exec line within the file, you have to add env --unset=GTK_USE_PORTAL, in order to execute Firefox in a proper way. So the line on the file have to be as follows:

Exec=env --unset=GTK_USE_PORTAL /usr/lib/firefox/firefox %u

After that you must reboot and then, open your firefox settings and try to set it as your default browser.

  • Thanks, did work for me - though the change had to be made under /home/usr/.local/share/applications/firefox.desktop – Tom May 9 at 18:29

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