Comment # 1 on bug 957041 from Raymond Wooninck

This is just simply caused by the fact that the appdata for dolphin is not
corresponding the filename of the desktop file for dolphin.  The appdata is
still dolphin.appdata.xml, but the desktop file is already called
org.kde.dolphin.desktop


This will be fixed with the upcoming KDE Applications release, but for now I
just rename the appdata file, so that the error will not show up anymore.