Plasma no longer boots: Could not load the Qt platform plugin “xcb” in “” even though it was found

[AlbertoSalviaNovella]

Manjaro KDE just upgraded to Plasma 5.21 with QT 5.15.2.

A friend of mine that uses Manjaro KDE told me that after today’s update, when he entered his password, the desktop was no longer initializing.

So I updated one of my computers myself, one that uses auto-login, and I got this:

When starting plasmashell from the tty I got:

Could not load the Qt platform plugin “xcb” in “” even though it was found.

The journal shows a problem with libc:

And the sddm.service shows:

Auth: sddm-helper exited with 1

[AlbertoSalviaNovella]

Fixed by removing kwin-lowlatency, and installing kwin.

They are telling me that the official kwin now has the benefits of lowlatency too.