Apparently, someone decided to split out the sddm-breeze theme into a separate rpm, and delete all the existing sddm-breeze theme files. So, if you aren't aware of this, and are using the sddm-breeze theme - you'll get a white screen upon reboot. You have to manually install the sddm-breeze rpm to fix it. I'll file a bug report... this is going to make many folks very unhappy.

On Fri, Sep 4, 2015 at 11:57 AM, Gerald B. Cox <gbcox@bzb.us> wrote:

This might explain it...
/usr/share/sddm/themes/breeze

now only has one file in it... theme.conf.user

Where did the other files go?

On Fri, Sep 4, 2015 at 11:44 AM, Gerald B. Cox <gbcox@bzb.us> wrote:
My /etc/sddm.conf has:

[Theme]
Current=breeze
CursorTheme=breeze

prior to the most recent testing updates, was working fine. Now
I get a blank white screen. By trial and error I found I needed to
comment out the above lines to be able to login normally.