Fresh Debian stable install on a virtual machine (VirtualBox on Pop_OS). First boot. Clicked on the Konqueror icon in the taskbar. The following error message appears: The operation couldn't be completed. Undocumented Error Unknown error code -600,818,432.
The problem is not Konqueror itself, as you can see launching Konqueror from KRunner (Alt-F2) or from the "Internet" section of Application Launcher (K menu). The behavior you see is caused from the fact that the icon on the taskbar (as the one in the "Favourite" section of the Application Launcher) points not to Konqueror itself but to an internal program used by Konqueror and which isn't supposed to be launched by the user because it requires a command line argument which can't be given when clicking on an icon.
(In reply to Stefano Crocco from comment #1) > The problem is not Konqueror itself, as you can see launching Konqueror from > KRunner (Alt-F2) or from the "Internet" section of Application Launcher (K > menu). The behavior you see is caused from the fact that the icon on the > taskbar (as the one in the "Favourite" section of the Application Launcher) > points not to Konqueror itself but to an internal program used by Konqueror > and which isn't supposed to be launched by the user because it requires a > command line argument which can't be given when clicking on an icon. OK thanks, so this should probably be reported to the Debian maintainers?
It's not a Debian issue, because after reading your bug report I found out the same happens on my Gentoo system, too (I usually start Konqueror using Krunner, so I never noticed that before). I'll have to investigate why the Application Launcher chooses the wrong program to put in the taskbar. As I know nothing about how the Application Launcher does so, I'll have to ask on the plasma mailing list. In the meanwhile, I've started a merge request (https://invent.kde.org/network/konqueror/-/merge_requests/122) which should fix the symptoms, if not the cause of the problem.
The root cause is in https://invent.kde.org/network/konqueror/-/blob/master/kfmclient_html.desktop sets up konqueror as default web browser (if no other is installed) as it associates with meta mime type `x-scheme-handler/http` and `x-scheme-handler/https` and the category `WebBrowser`. It is why it is shown in the favorites. And a webbrowser app is expected to be opened without any argument. The fix in https://invent.kde.org/network/konqueror/-/merge_requests/122 fixed the issue, since now kfmclient support this use case just fine.