I go to break out /var to have it mounted separatly by fstab.

When I boot, root can log in Roos can log to windos manager. But user's log in fails.

$ starx or $ startx fluxbox both have fatal server error becaise X
could not create lock file /tmp/.tX0-lock

The /tmp/ usally has a serverauth.* file owned by user, but that is missing now.

My prcedure for breaking /tmp out

  I check to make sure nothing is mounted on /mnt
  I mount the devide on /mnt
       # mount /devc/nvme1n1p5 /mnt
  I run $ lsblk -f to fine ther UUID of the /tmp partition /dev/nvme1n1p5:
  I edit /etc/fstab to have the UUID mount on /tmp
    UUID=NNNNNNNN  /tmp   ext4  0  2
  I copy the content of /tmp to /mnt
    # rsync -avX  /tmp  /mnt --exclude=lost+found
        # umount /mnt
  reboot 

I suspect the necessary lock file could't be created in /var becasue
of the absense of the serverauth.NNN file.

User does have a Xauthority file owned by user

Some one solve the problem by using sysrc sddm_enable="YES"

I find in /usr/bin/startx in Create a file with auth information the line

serverauthfile='mktemp --tempdir serverauth.XXXXXXXXX'

Apparently this is normal

Someone suggested Alt-Ctl=F1, then sudo pkill -9 Xorg, then startx, but
I dont'know what this does and so hesitated to try it.

Another thing I did't dare was to remove the .Xauthority file in my
home directory.

ownership and permistions for /tmp seem OK likewise for /var/tmp

in /tmp there is no locak file or serverauth.NNN file

--
Haines Brown