hello, how install Greek characters and how to switch Greek-English?

[leszek]

Sorry I don't understand Greek. Can you run the update with English language.
You can do so by running the command like this

Code:

LC_ALL=C sudo apt-get upgrade

Also do you have the system installed on hdd/ssd or do you run a live USB stick. If the latter than grub update will always fail as grub isn't installed at all on the stick.