Comment # 1 on bug 1095678 from Isamu Koga

I experienced similar issue related to this topic.

I have tried to upgrade from Leap 42.3 to 15.0 from Network install by USB
stick however YaST2 stopped when I came across ���Select for Update��� display.  I
attach a y2log.

It seems to be related encrypted partition (LUKS).  I could avoid this issue if
I follow the steps below:

1. Boot system and commented out encrypted partition from /etc/fstab.
2. Restart system and boot from USB stick.
3. Choose Upgrade and cancel for password prompt to pass the dialog.
4. Boot Leap 15.0 and restore /etc/fstab.

I could do this workaround because my encrypted partition was /home.

I think similar bugs were reported: #1094749 #1095678 #1095685