Created attachment 728882 [details]
y2logs

issue: There is an error message when try to open "yast disk" 
                Error  Internal error. Please report a bug report with logs.  

                        Run save_y2logs to get complete logs.

                        Details: undefined method `split' for nil:NilClass   

                        Caller: 
/usr/share/YaST2/modules/FileSystems.rb:2114:in `btrfs_subvol_name_for'

reproduce steps:

1.create 2 new partitions /dev/sda7 and /dev/sda8

2.mkfs.btrfs /dev/sda7 /dev/sda8

3.mount /dev/sda7 /mnt/backup

4.mount /dev/sda8 /mnt

5.yast disk

Note:Ext4 and XFS do not have this issue,only btrfs failed.