I have a double system on my SSD, Windows and Linux.

This also isn't the first time I try to install a LUKS LVM debian system, previously grub could at least create a boot menu entry for Windows but Debian didn't work proberly so I have re-installed it once again, but this time os-prober cannot detect neither system.

The first issue that I've encountered with this latest instance of my system is that in the installer environment grub couldn't be installed due to some error, so I've just ignored it and after completing the installation I've entered chroot from a live system to install grub manually.

This is the command I've used:

#grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=grub --recheck --debug

Then:

#sudo update-grub

Which returned:

#Generating grub configuration file ...
#Found background image: .background_cache.png
#Warning: os-prober will be executed to detect other bootable partitions.
#Its output will be used to detect bootable binaries on them and create new boot entries.
#grub-probe: error: cannot find a GRUB drive for /dev/sda1. Check your device.map.
#Adding boot menu entry for UEFI Firmware Settings ...
#done


/dev/sda1 is most probably the USB drive that hosts my live system but why isn't debian detected even if it's UEFI (it contains the efivars directory)? I don't care about fixing teh boot entry for windows right now but I really need debian to work.

Even unmounting and unplugging teh live USB doesn't fix anything, the related error just doens't appear.

What error? Did you create a mount point and mount the efi partition before running the command and if sda is your usb, what is your internal drive shown as? It would help other members viewing to help you if you post all the command to chroot/ mount and install grub.

Well that error appeared while inside the Debian's installation environment on USB, and I don't have a screenshot.

To mount the chroot system I've simply used the "cryptsetup luksOpen" command and followed this guide for the rest https://wiki.debian.org/GrubEFIReinstall

But anyway, I've found out the solution for my problem when I've noticed there was no kernel or initrd image on my efi partiton.
I'm pretty sure that during my previous attempts I had those two files, maybe they didn't work because they were corrupted or missing some links? I don't know, but the important is that after reinstalling the kernel and regenerating initrd I could successfully add Debian to grub's menu and now my luks LVM system is finally working.