Links in Telegram have been opening random apps (image viewer, Calibre, etc), so I checked System Settings > Applications > Default Applications > Web Browser.

Open URLs "in an application based on the contents of the URL" sounds like the culprit, so I changed to "in the following application (Firefox)".

However after leaving this screen or rebooting (both) the setting reverts:


I ran system settings from console, but I couldn't see any obvious errors.

Update: I ran a fresh install of Kubuntu 18.04 in a virtual machine and tried this, with the same result. Did all available updates and rebooted, tried it again - same result - even though it was on a fresh, stock system.

  • I think this is a bug, and it's new in Kubuntu 18.04. This stuff used to work in Kubuntu 17.10 and 17.04. Aug 18, 2018 at 13:42
  • Out of curiosity, what did you use to record the screen? Aug 18, 2018 at 13:55
  • 1
    @ChristianHujer I believe it was SimpleScreen Recorder maartenbaert.be/simplescreenrecorder
    – Merritt
    Aug 19, 2018 at 14:15

5 Answers 5


Not ideal but I used the with the following command: option on Default Applications dialog in Kubuntu 18.04. For Firefox I would assume this would work: /usr/bin/firefox %s. I prefer Google Chrome so I used: /usr/bin/google-chrome %s

Screenshot of Default Applications dialog in Kubuntu 18.04


What was helping me: (I am using Kubuntu 18.04 LTS) find the following file /home/USERNAME/.config/mimeapps.list and edit it like this:

[Default Applications]

The last two x-scheme-handler/... lines were empty for me, so I wrote google chrome there as I prefer chrome.


This bug appears to be resolved in 18.04.3


I experienced the same issue. It looks like a bug.

What helped me was clicking on "File Associations" after "Apply" and then again on "Default Applications". I noticed that my change was applied. After that I closed the settings window and opened it again. My change was still there.

PS: I could reproduce the issue even in 16.04 LTS


I encountered a similar issue. For me, it was due to the file ~/.config/mimeapps.list not owned by me.
And it was the only file in this folder not owned by myself.
So I changed the file owner:

cd .config/
sudo chown myUserName:myUserGroup mimeapps.list 

And then I could update my default applications.

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