In KDE systemsettings > Personalization > Applications > Default applications > Web browser, there are two settings: A) "in an application based on the contents of the URL". B) "in the following browser". There are two problems with the interface: 1- if A) is selected, then the name of the default browser is not visible. 2- It is not possible to change the default browser and keep A) selected. To do so, the workaround is to select B), type in the browser name, save, then select A) again, save again. When coming back later to the same screen, the first problem occurs again. http://linux.overshoot.tv/wiki/default_browser_kde
Logically, the settings should be split into two different settings: - One setting to select the default browser. - One setting to select default action, with A) as above and B) reading: "in the default browser".
Where are the relevant settings saved? I checked ~/.config/systemsettingsrc but it does not appear to be there.
While dealing with Bug 393727 I have noticed the issue described in this bug report is valid for Plasma 5.12 on Kubuntu 18.04. I have Firefox and Falkon installed on my system. When I choose Falkon "in the following application" drop-down of Default Applications > Web Browser, links open in Falkon as expected. If I choose the "in an application based on the contents of the URL" option, links open in Firefox.
*** This bug has been marked as a duplicate of bug 100016 ***