Dual-boot: GRUB shows Windows boot manager but Windows doesnt boot

[x-achilles-o]

Hey fellow community!

This is my first post here, Im not really new to Ubuntu (already use it on my old Macbook and installed Xubuntu years ago alongside Windows 7), still consider myself a rookie.

As I got my hands on a great offer - iMac 16,2 2015 with already installed Win11 - I was eager to install Ubuntu alongside with it following the article series of the magazine c't 18/2022 where they give instructions to setup Linux alongside Windows: Windows already encrypted by BitLocker, clear up some space from the SSD for a shared safe partition and then install Ubuntu and encrypt it with VeraCrypt.
It all went fine til after the installation of Ubuntu: the installation process went flawless but after first start I encountered several issues. One of them is that Windows doesnt boot anymore. GRUB shows the menu entry "Windows boot manager /dev/sda1" but when I select it it only leads to a black screen and nothing happens, even after a minute waiting so the only OS bootable is Ubuntu (select it in GRUB, entering a busybox shell and encrypting sda8_crypt with

cryptsetup luksOpen /dev/sda8 sda8_crypt

)
I tried fixing it by running boot-repair on Ubuntu and this is what the process summarizes:
https://paste.ubuntu.com/p/ZBjp222dQb/ or

boot-repair-4ppa2075                                              [20240204_1753]
============================= Boot Repair Summary ==============================
User choice:
Is there RAID on this computer? no

==================== blkid (filtered) before lvm activation ====================
/dev/mapper/vgubuntu-root: UUID="f5dc8cca-...-59359551ba19" BLOCK_SIZE="4096" TYPE="ext4"/dev/sdb1: LABEL="USBSAFE" UUID="5A28-EA70" BLOCK_SIZE="512" TYPE="vfat" PARTUUID="..."/dev/mapper/vgubuntu-swap_1: UUID="a8af5fea-...-d4e8871fab6f" TYPE="swap"/dev/mapper/sda8_crypt: UUID="cmEfB3-...-JXvt-nWmnDZ" TYPE="LVM2_member"/dev/sda4: TYPE="BitLocker" PARTLABEL="Basic data partition" PARTUUID="7c425185..."/dev/sda7: UUID="cbb86dcb-...f4541" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="cea0a422-...d47"/dev/sda5: LABEL="ctRecovery" BLOCK_SIZE="512" UUID="..." TYPE="ntfs" PARTLABEL="Basic data partition" PARTUUID="aa2bdf38-..."/dev/sda3: TYPE="BitLocker" PARTLABEL="Basic data partition" PARTUUID="8f03d0db-..."/dev/sda1: UUID="5A1D-58F8" BLOCK_SIZE="512" TYPE="vfat" PARTLABEL="EFI system partition" PARTUUID="e0259722-...-14e7b628e5c5"/dev/sda8: UUID="e4c4ea47-..." TYPE="crypto_LUKS" PARTUUID="927649fd-..."/dev/mapper/winlin-data: LABEL="winlindata" BLOCK_SIZE="512" UUID="..." TYPE="ntfs"/dev/sda2: PARTLABEL="Microsoft reserved partition" PARTUUID="2e9d0c54-..."/dev/sda6: PARTLABEL="Basic data partition" PARTUUID="bae5ac82-..."

================================ LVM activation ================================
modprobe dm-mod  vgscan --mknodes  Found volume group "vgubuntu" using metadata type lvm2vgchange -ay  2 logical volume(s) in volume group "vgubuntu" now activelvscan  ACTIVE            '/dev/vgubuntu/root' [87.89 GiB] inherit  ACTIVE            '/dev/vgubuntu/swap_1' [<8.82 GiB] inheritblkid -g



modprobe: FATAL: Module efivars not found in directory /lib/modules/6.5.0-15-genericEFI variables are not supported on this system.
Recommended repair: ____________________________________________________________
The default repair of the Boot-Repair utility will purge (in order to enable-lvm) and reinstall the grub-efi ofmapper/vgubuntu-root,using the following options:  sda7/boot sda1/boot/efiAdditional repair will be performed:  unhide-bootmenu-10s use-standard-efi-file

/dev/mapper/vgubuntu-root/boot/efi not emptyapt-get -y updatePurge the GRUB of /dev/mapper/vgubuntu-rootgrub-efi availablePaketlisten werden gelesen…Abhängigkeitsbaum wird aufgebaut…SET@_progressbar1.pulse()
Statusinformationen werden eingelesen…Die folgenden zusätzlichen Pakete werden installiert:grub-efi-amd64Die folgenden Pakete werden ENTFERNT:grub-gfxpayload-lists grub-pcDie folgenden NEUEN Pakete werden installiert:grub-efi grub-efi-amd640 aktualisiert, 2 neu installiert, 2 zu entfernen und 4 nicht aktualisiert.Es müssen 49,4 kB an Archiven heruntergeladen werden.Nach dieser Operation werden 419 kB Plattenplatz freigegeben.Holen:1 http://de.archive.ubuntu.com/ubuntu jammy-updates/main amd64 grub-efi-amd64 amd64 2.06-2ubuntu14.4 [47,1 kB]Holen:2 http://de.archive.ubuntu.com/ubuntu jammy-updates/main amd64 grub-efi amd64 2.06-2ubuntu7.2 [2.240 B]Herunterladen abgeschlossen; Nur-Herunterladen-Modus aktivDEBCHECK debOK, grub-efiDEBCHECK debOKPlease type: sudo dpkg --configure -ansudo apt-get install -fynsudo apt-get install -y lvm2nsudo apt-get purge --allow-remove-essential -y grub-com*nsudo apt-get purge --allow-remove-essential -y grub2-com*nsudo apt-get purge --allow-remove-essential -y shim-signednsudo apt-get purge --allow-remove-essential -y grub-common:*nsudo apt-get purge --allow-remove-essential -y grub2-common:*nThen type: sudo apt-get install -y grub-efi os-proberNo /dev/mapper/vgubuntu-root/etc/default/grub
Unhide GRUB boot menu in mapper/vgubuntu-root/etc/default/grub
======== Reinstall the grub-efi os-prober of /dev/mapper/vgubuntu-root =========
grub-install --versiongrub-install (GRUB) 2.06-2ubuntu7.2modprobe: FATAL: Module efivars not found in directory /lib/modules/6.5.0-15-genericmodprobe efivars
efibootmgr -v before grub installEFI variables are not supported on this system.

uname -r6.5.0-15-generic
grub-install --efi-directory=/boot/efi --target=x86_64-efiInstalling for x86_64-efi platform.grub-install: warning: EFI variables cannot be set on this system.grub-install: warning: You will have to complete the GRUB setup manually.Installation finished. No error reported.cp /boot/efi/efi/ubuntu/grubx64.efi /media/stevie/USBSAFE/EFI/ubuntu/grubx64.efidf /dev/sda1mv /boot/efi/EFI/Boot/bootx64.efi /boot/efi/EFI/Boot/bkpbootx64.eficp /boot/efi/efi/ubuntu/grubx64.efi /boot/efi/EFI/Boot/bootx64.efidf /dev/sdb1touch /media/stevie/USBSAFE/EFI/Boot/bootx64.efi.grbcp /boot/efi/efi/ubuntu/grubx64.efi /media/stevie/USBSAFE/EFI/Boot/bootx64.efi
grub-install --efi-directory=/boot/efi --target=x86_64-efiInstalling for x86_64-efi platform.grub-install: warning: EFI variables cannot be set on this system.grub-install: warning: You will have to complete the GRUB setup manually.Installation finished. No error reported.
efibootmgr -v after grub installEFI variables are not supported on this system.
Warning: NVram is locked (Ubuntu not found in efibootmgr).
update-grubSourcing file `/etc/default/grub'Sourcing file `/etc/default/grub.d/init-select.cfg'File descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37436: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37436: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37440: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37440: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37443: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37443: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37447: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37447: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37483: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 37483: /usr/sbin/grub-probeFound linux image: /boot/vmlinuz-6.5.0-15-genericFound initrd image: /boot/initrd.img-6.5.0-15-genericFound linux image: /boot/vmlinuz-6.2.0-26-genericFound initrd image: /boot/initrd.img-6.2.0-26-genericFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 38042: /usr/sbin/grub-probeFile descriptor 63 (pipe:[83117]) leaked on vgs invocation. Parent PID 38042: /usr/sbin/grub-probeFound Windows Boot Manager on /dev/sda1@/EFI/Microsoft/Boot/bootmgfw.efi
Unhide GRUB boot menu in mapper/vgubuntu-root/boot/grub/grub.cfg
Bootsektor wurde erfolgreich repariert.
Locked-NVram detected. Please do not forget to make your UEFI firmware boot on the Das aktuell benutzte Betriebssystem - Ubuntu 22.04.3 LTS entry (sda1/efi/ubuntu/grubx64.efi file) !

============================ Boot Info After Repair ============================

As Im feeling a little frustrated from searching a solution through the internet (because I feel theres no solution or the cases not really resemble mine) and overwhelmed Im posting my problem here now hoping for individual help for my exact case. I really tried to do it on my own but now I need a little support by experienced people, at least solving one of my issues.

[oldfred]

Do not know Mac, but can you boot Windows directly from a UEFI boot menu, not grub.

Grub only boots working Windows. That also means Windows cannot be hibernated or fast boot which also sets hibernation flag nor encrypted if Windows has encrypted its ESP - efi system partition.

[x-achilles-o]

Do not know Mac, but can you boot Windows directly from a UEFI boot menu, not grub.

Grub only boots working Windows. That also means Windows cannot be hibernated or fast boot which also sets hibernation flag nor encrypted if Windows has encrypted its ESP - efi system partition.

Unfortunately, no :'( when I enter UEFI there are two options: one is called WINDOWS (Im guessing its the integrated SSD) and one is an orange drive symbol called EFI boot. When I chose WINDOWS the grub menu shows with options Ubuntu, advanced options for ubuntu and Windows boot manager. When I chose EFI boot, I get the minimal bash of GRUB presented.
When I check disks via Ubuntu OS, it shows the Windows partitions, so Im confused: is Windows still there, can I "just not" enter it?

[oldfred]

With advanced options grub menu can you boot recovery mode?

I thought Mac were UEFI only, so not sure why you are getting this error?

EFI variables are not supported on this system.

Do not know LVM either.

You can try a full chroot. Probably some combination of UEFI & LVM mounts required.
UEFI chroot, must include ESP - efi system partition
http://askubuntu.com/questions/53578...er/57380#57380
chroot with UEFI, LVM, encryption on NVMe drive
https://ubuntuforums.org/showthread....8#post13602088
To chroot, you need the same 32bit or 64 bit kernel. Best to use same version.
https://help.ubuntu.com/community/BasicChroot

[x-achilles-o]

With advanced options grub menu can you boot recovery mode?

No, I cant, I assume due to my other problem: every time I wanna boot Ubuntu I get into a busybox shell with an initramfs prompt and need to encrypt the partition with

cryptsetup luksOpen

. When I tried to start Ubuntu in recovery mode it says

Volume group vgubuntu not found... cannot process volume group vgubuntu... gave up waiting for root file szstem device... ALERT! /dev/mapper/vgubuntu-root does not exist.

As cryptsetup is not a built in command in this scenario I dunno how to get Ubuntu started in recovery mode.
Im getting the feeling that my problem is bigger than I thougt

Edit: due to a family issue I couldnt handle the issue further, still Ubuntu offered a system upgrade from 22.04. to 23.10. When the iMac starts now, no GRUB is showing, instead Im getting a window where Im asked to unlock the partition (so not booting into a busy-box shell like before). Should I still perform the suggested chroot?