I decided a reinstall would be easier. I installed from the latest siduction testbuild of lxqt, added a few packages (streamtuner2, vlc, mpv, opera, chrome,hexchat, kpat, and meteo-qt). I did d-u in init 3 before restoring my data. Unfortunately the same thing happened. I probably should have kept the system and looked at startx log. However, I installed mxlinux. I still have not restored the data. This is an older Dell desktop with intel i5 and AMD graphics. Yesterday there were about 22 upgrades including sddm if I remember. On the original system I had done the xorg and i think also the qt upgrades days ago with no problem.