I've tranversed the internet looking for solutions for this.

I issue, under user name, in Konsole:

sudo kate

and I get this:

Error: "/var/tmp/kdecache-amer" is owned by uid 1000 instead of uid 0.
Error: "/tmp/kde-amer" is owned by uid 1000 instead of uid 0.
Error: "/tmp/kde-amer" is owned by uid 1000 instead of uid 0.
Error: "/tmp/ksocket-amer" is owned by uid 1000 instead of uid 0.
kdeinit4: Shutting down running client.
Connecting to deprecated signal QDBusConnectionInterface::serviceOwnerChanged(QString,QString,QString)
Error: "/tmp/ksocket-amer" is owned by uid 1000 instead of uid 0.
Error: "/tmp/kde-amer" is owned by uid 1000 instead of uid 0.
Error: "/var/tmp/kdecache-amer" is owned by uid 1000 instead of uid 0.
kbuildsycoca4 running...
Error: "/var/tmp/kdecache-amer" is owned by uid 1000 instead of uid 0.
Error: "/var/tmp/kdecache-amer" is owned by uid 1000 instead of uid 0.
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
QFileSystemWatcher: failed to add paths: /home/amergin/.config/ibus/bus
kate(1505)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x9c5144c deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.
kate(1505)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x9da39d0 deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.
kate(1505)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x9ca64fc deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.

And if I'm root and issue at Konsole "Kate"

The response is this:
No protocol specified
kate: cannot connect to X server :0

Thanks for your considered response in helping me sort this out.

Kate, does work under user name, but never on "su"

Cheers

try "kdesudo kate" instead of sudo.

claydoh wrote:try "kdesudo kate" instead of sudo.

I did and got this:
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
QFileSystemWatcher: failed to add paths: /home/amer/.config/ibus/bus
QInotifyFileSystemWatcherEngine::addPaths: inotify_add_watch failed: No such file or directory
QFileSystemWatcher: failed to add paths: /root/.config/ibus/bus
kate(12481)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x85f2dc4 deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.
kate(12481)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x87454b0 deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.
kate(12481)/kdeui (kdelibs) KXMLGUIClient::~KXMLGUIClient: 0x8647d6c deleted without having been removed from the factory first. This will leak standalone popupmenus and could lead to crashes.

And when I tried it with "su", got this:
No protocol specified
kdesudo: cannot connect to X server :0

I think if you use sudo instead of using kdesu and run gui apps you eventually get the "Error: /var/tmp/kdecache-amer" is owned by uid 1000 instead of uid 0"

I would logout, then log in as root in non gui mode (failsafe login) delete /var/tmp/kdecache-amer & /tmp/kde-amer then make sure all my KDE config files have proper ownership by running chown -R /home/amer/.kde amer,logout then login as amer and in konsole run kbuildsycoca4 --nonincremental

As stated, KDE applications must never be run using "sudo", but using either "kdesu" or "kdesudo" depending on your system.