Created attachment 132865 [details] Example KMZ SUMMARY The thumbnailer does not work even for trivial, valid files marble itself has no problems with. STEPS TO REPRODUCE Enable KML preview in dolphin, try preview on attached file OBSERVED RESULT Thumbnailer blocks for 5 seconds on the file, then returns nothing EXPECTED RESULT Thumbnail created SOFTWARE/OS VERSIONS Linux/KDE Plasma: openSUSE TW 20201026 KDE Plasma Version: 20.08.02 KDE Frameworks Version: 5.75 Qt Version: 5.15.1 ADDITIONAL INFORMATION The marble thumbnailer tries to geocast the returned KmlDocument to a GeoDataDocument, which fails.