packagekit error when updating KDE:Extra on Tumbleweed

I’m getting an error lately when trying to check for updates from the “Software updates” tray app (KDE). The message says something like " Can’t establish a secure link with the software source. Check your signing preferences" (This is a translation)
In the journal log I can see the following error:

mar 28 16:24:05 linux-o4hn packagekitd[9530]: KDE_Extra: [KDE_Extra|http://download.opensuse.org/repositories/KDE:/Extra/openSUSE_Tumbleweed/] Valid metadata not found at specified URL

Anyone using KDE:Extra Repository on Tumbleweed having the same issue? Any idea how to solve it?

kde extra just updated the gpg key which may explain things.
just in case: be sure to use sudo zypper dup --no-allow-vendor-change to update TW (Package kit or zypper up will eventually screw up your system. the dup will also allow import of new key (if this is the problem)

There was a bug in libzypp that caused it to delete accepted keys by mistake, in particular in combination with PackageKit.
Should be fixed by a recent update…

https://bugzilla.opensuse.org/show_bug.cgi?id=1036659