Created attachment 759721 [details]
Log file from save_y2logs

After updating of whole distibution (Tumbleweed) I can't access "Boot loader"
section of YaST. Probably (by error code), it can not process letters from the
cyrrhic alphabet in the title of the boot section. I set all regional settings
to English / US, but it doesn't help. During installation of openSUSE, one of
the GRUB menu items was automatically named as "Windows 7 ���� /dev/sda1" ("����" -
possible cause of the failure).
If you need any additional files for diagnosis, please write.

Software versions:
yast2-bootloader - 4.0.15-1.1
yast2 - 4.0.49-1.1

Error code:

/usr/lib/YaST2/bin/y2start:58:in `<main>'
2018-02-11 21:12:59 <3> compik(23411) [Ruby] yast/wfm.rb:276 Internal error.
Please report a bug report with logs.
Run save_y2logs to get complete logs.
Details: invalid byte sequence in US-ASCII
Caller: 
/usr/lib64/ruby/gems/2.5.0/gems/cfa_grub2-0.6.5/lib/cfa/grub2/grub_cfg.rb:18:in
`==='