I went via the command line and ventured to keep all additional repos enabled. So switching the repos was done simply by
sed -i "s/11\.2/11.3/g" /etc/zypp/repos.d/*
The KDE session crashed after kdelibs4-core had been updated. No big deal, so I ran
The /home directory is mounted via NFS, so filesystem.rpm failed when it wanted to reset the permissions of /home. Updating it explicitly after unmounting /home was easy, only unmounting it was harder because the crashed session left processes still accessing the home.
fuser -v /homefound them.
The NFS mount is also authenticated by Kerberos and there is a bug so I got
mount.nfs: access denied by server while mounting nfs.example.com:/homeI had to rebuild and update a package and tweak a config file. See bnc#614293 for the details (thanks to mcaj for the reference).