Installing Ubuntu 18.04.2 LTS on Acer, GRUB 2 package is hanging

Since yesterday I try to install Ubuntu 18.04.2 LTS on my Laptop Acer Swift 1 where I had Windows 10 previously. Initially I had some problems with the installation start, but I disabled “secure boot” and it worked. however, now the Ubuntu starts installing and everything goes smooth, but then the installation suddenly stops the progress and I get “Installing the grub2 package”. This can last hours without any progress.

I tried to open the Terminal in the background and typed the commands:

sudo fdisk -l sudo mount /dev/sdxY /mnt  (where x is altter and Y a number you have found in the previous step) sudo grub-install --root-directory=/mnt /dev/sdx  sudo update-grub 

Well, this did not work. An error message occurred: “grub-install error: will not proceed with blocklists”.

I have swap area, ext4 space and EFI space. Separating my free space into these categories did not help too. How can I finally install the Ubuntu? What should be done? I get almost to the final stage, but the grub2 packages can not be installed.