IN OpenSuse 15.2 I need to umount the / partition but I am getting device busy errors which block umount.

Its Ext4 so I should be able to fsck this problem once unmounted.  Then I can finish backing up the /home and proceed to upgrade to 15.5.

How do I correct this device busy problem?

The system crashed and shut off during a Firefox secession I think I had too many tabs open.


CWSIV