Can't boot from non-encrypted disk

So I did what you proposed.
I used manjaro-chroot -a from live ISO and executed those two commands.
Works fine at the first boot from HDD.
At the second boot I got these messages again:

error: no such device: here is a long hexadecimal number...
error: file '/boot/vmlinuz-5.10-x86_64' not found
press any key for continue

If I boot again from live ISO and use the manjaro-chroot the system is booting again from HDD.
No need the pacman commands to be executed, the boot is OK again.
This lasts until the next boot. Then I must to first boot live ISO and after that I can boot again from HDD.
What is the soluution?

How do you shutdown / reboot, exactly?

There is a Manjaro menu button that gives an option to reboot.

This looks to me that either during boot or shutdown your system gets damaged, hard to say how this could happen. :man_shrugging:

I would really appreciate a working solution, because to recreate the system with install from the scratch would be 3-4 weeks for me.

Just one question:
If I upgrade the kernel, that makes a new boot block, would help that, or even the situation will be worse?