https://bugs.kde.org/show_bug.cgi?id=413690
--- Comment #15 from Ismael Asensio <isma...@gmail.com> --- I was experiencing this same issue, but with Firefox. The issue seems to be, as the comments suggest, that the preferred application for that category (mail viewer in your case) do not have an icon, so the `ApplicationServiceTrader` cannot find a valid icon to show in the preview. If, in the "Preferred applications" page, the combobox shows no icon for that category, very likely the window switcher will not show it either. I could fix the issue by: 1. Found an old version of `firefox.desktop` on `.local/share/applications` with no "Icon=firefox" key within. 2. Delete that .desktop file 3. In "Preferred Applications", find and select "Firefox Web Browser" from the list of applications (again, as it is probably a different desktop file, this time, with the correct icon). 4. After that, running `kbuildsycoca6 --noincremental` to rebuild the internal cache (maybe restarting the session too) If you'd like, you can check if there is such a similar stray .desktop file that is messing with the icon for your preferred email client. As a failsafe we could use the fallback icon (and app name?) for the previews if the icon is missing. They're just placeholders to showcase the switcher anyway. -- You are receiving this mail because: You are watching all bug changes.