I received this error last night during compiling using *.sprc file. ;----------- /root/rpmbuild/BUILDROOT/xfce4-terminal-0.8.7.4-3.fc29.i386/usr/share/applications/xfce4-terminal-settings.desktop: error: file contains key "NotShownIn" in group "Desktop Entry", but keys extending the format should start with "X-" Error on file "/root/rpmbuild/BUILDROOT/xfce4-terminal-0.8.7.4-3.fc29.i386/usr/share/applications/xfce4-terminal-settings.desktop": Failed to validate the created desktop file ;----------- The validation wasn't able to pass, because the desktop file contained some unknown attributes. The xfce4-terminal from a couple of days ago compiled finde. Maybe you could have a look ?
According to https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html as well as a grep under my /usr/share/applications, the correct spelling of the keyword is "NotShowIn" (one fewer "n"). RIP English grammar :)
Igor referenced this bugreport in commit 7b03eeb47dee82ac90e4ec776863dd27559bcfa2 Fix typo in the .desktop file https://git.xfce.org/apps/xfce4-terminal/commit?id=7b03eeb47dee82ac90e4ec776863dd27559bcfa2
Ali, thanks for the report! Egmont, thanks for the info! Right on point, as usual :)