How to install kubuntu 20.04.1 on second hard and avoid grub-install /dev/sda failed error?

Question

Kubuntu

Good afternoon,

I have a stationary computer with two hard drives.
1) 450_GB - SSD
2) 1_TB - philistine

On 1) installed Windows 10 .
On 2) I tried to install kubuntu 20.04.1
[earlier I installed it on 2) mint 19 , but for some reason the GUI slowed down, I decided to install a more familiar kubuntu - like on a working laptop] I recorded an image with a fresh kubuntu on a flash drive

on a working laptop using the dd utility . I went into the BIOS , assigned the highest priority to the flash drive and rebooted. [ Additionally, I provide screenshots from the BIOS / BOOT.


In the expanses of tyrnet I read that Fast BOOT and Secure BOOT are disabled for correct installation ]

1)


2)


3)


Next, in order not to fall into a black screen, I press the grub menu on the first item with Kubuntu - the e key

I write additionally in a text editor:

$vt_handoff nomodeset acpi=off pcie_aspm = off

I press F10 and I get into the installer.
[ Before the ugly one appears: Initramfs unpacking failed: Decoding failed . But it passes]

After selecting the language, etc. I get into partition management.
windows 10 (450_GB - SSD) - / dev/sda
[ screen with a list of its partitions, maybe it will be useful) ]



Disk underkubuntu (1_TB - whole SSD) - /dev/sdb
Marked as follows:

/dev/sdb
- /dev/sdb1     ext4      /boot     1GB
- /dev/sdb2     efi                       500MB
- /dev/sdb5     swap                   32GB 
- /dev/sdb6     ext4     /home     700GB
- /dev/sdb4     ext4     /              266GB

Below is an interesting thing, the meaning of which I do not quite understand:

Device for boot loader installation - by default / dev/sda
( windows SSD 450GB ) by default, my version of what it means - what will be added to the start grub / grub gui of course I can make mistakes, but otherwise I would not ask =) ]

And that's it. Next, fill in the username, computer and password.
Installation in progress .......
and at a certain stage a caring window pops up with the inscription:

Executing 'grub-install / dev/sda' failed
This is a fatal error


Tried to change during installation
Device for boot loader installation - to the currently installed disk /dev/sdb 1_TB)
As a result, the error changes to:

Executing 'grub-install / dev/sdb' failed
This is a fatal error


Please help, dear Linux specialists!