Can no longer boot into Kubuntu

[jim204]

Hi,

I recently tried to do an upgrade from v22.04 LTS to the latest version by following the below steps. (There might be another step missing as I asked chatgpt for the process, and I can't find that history.)

sudo apt update && sudo apt upgrade -y
sudo apt install update-manager-core


Anyway, after doing so, before doing the actual upgrade, I was asked to reboot. Upon rebooting, the grub boot loader stopped showing up. (I have two operating systems, Windows 10 and Linux which are installed on different physical drives. The screen would just go black, and it would reboot into bios.

Next I tuned the computer on, this time I manually pressed (F12), to choose the boot sequence, and I chose the windows 10 boot manager drive. When trying to boot into windows I got the bitlocker encryption message, saying some hardware/system settings have changed, prompting me to enter my recovery key. In doing so, I can boot into windows, but still not kubuntu and my grub bootloader is gone.

I am not sure if the bitlocker drive encryption is source of the reason kubuntu will no longer boot, or its a coincidence in timing, and the reason is down to me trying to update.

So in summary,

- Tried to update Kubuntu
- Rebooted and am no longer able to boot into kubuntu (I just get a black screen and it reboots back into bios)
- Have fixed the bitlocker encryption and have now turned it off (so the drive is no decrypted).

Any ideas on where I should start in trying to solve this problem?

Let me know if there is any details I have missed in helping me out with this issue.

[spiderman]

I read a similar post where a user had an AUS that after a MS update to windows, they filled up the NVRAM so no other systems would boot except windows. This user had to go into the bios and open up secure boot, then edit OR clear out all the boot entries in the bios secure boot section. All bios is different, but they may have similar layouts. Secure boot is not needed for Ubuntu or WINXXX), but if that gets filled up for some reason (because you are dual boot) you may have these types of issues. What are the details of your machine/bios? Refered to issue here: https://www.kubuntuforums.net/forum/...23-04-10-24-04

[jim204]

Thanks for you reply.

Regarding the secure boot, I have looked everywhere in bios and I can't find this secure boot option, or any mention of keys. My motherboard is Gigabyte x570 Gaming X running the F35 version.

Since making this post, I have created a live Kubuntu usb which I can boot into, and have access to a terminal. I tried to reinstall grub, but when doing so, I got a message saying "EFI variables cannot be set on this system". Hope this helps, please advise any other suggestions

[Qqmike]

I am no longer familiar with Windows nuances, especially with booting issues.
However ... it sure sounds to me that you do not have an EFI/UEFI system.
It sounds like you have a legacy (older) GRUB system (and regular BIOS on your computer).
In any case ... a good thing to do (while waiting on perfect clarity) would be to use Boot Repair.
See here:
https://help.ubuntu.com/community/Boot-Repair
It has it's plusses and minuses, but overall it could easily shed some light on what's going on.
(You can also try some things from your live Kubuntu USB, but that can get messy or more advanced/tricky.)

[spiderman]

Also, I used a boot repair disk I got from source forge dot net... ( https://sourceforge.net/projects/boot-repair-cd/ ) and it did a great job for me. Let us know how it goes. QQ is right, sounds like the legacy boot and UEFI boot got mixed up.

[jim204]

I checked in windows and it appears I have a EFI/UEFI system (see attached). I am going to try the boot repair as suggested to provide more info

[jim204]

I am having issues logging in to view the report, but here it is.

https://paste.ubuntu.com/p/VrQGTkJkRm/

[Snowhog]

I am having issues logging in to view the report, but here it is.

https://paste.ubuntu.com/p/VrQGTkJkRm/

That link isn't 'public', it requires the viewer to have a UbuntuOne account (I do), so I'm providing it here.

boot-repair-4ppa2081 [20241001_1041]

============================== Boot Info Summary ===============================

=> Windows is installed in the MBR of /dev/nvme0n1.
=> Windows is installed in the MBR of /dev/nvme1n1.
=> Windows is installed in the MBR of /dev/sda.
=> Windows is installed in the MBR of /dev/sdb.
=> Grub2 (v2.00) is installed in the MBR of /dev/sdc and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and looks
for (hd0,msdos1)/boot/grub. It also embeds following components:

modules
---------------------------------------------------------------------------
biosdisk fshelp fat exfat ext2 ntfs ntfscomp part_msdos
---------------------------------------------------------------------------

nvme0n1p1: _____________________________________________________________________

File system: ntfs
Boot sector type: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

nvme0n1p2: _____________________________________________________________________

File system: vfat
Boot sector type: FAT32
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files: /efi/Boot/bootx64.efi /efi/Boot/fbx64.efi
/efi/Boot/mmx64.efi /efi/ubuntu/grubx64.efi
/efi/ubuntu/mmx64.efi /efi/ubuntu/shimx64.efi
/efi/ubuntu/grub.cfg /efi/Microsoft/Boot/bootmgfw.efi
/efi/Microsoft/Boot/bootmgr.efi
/efi/Microsoft/Boot/SecureBootRecovery.efi

nvme0n1p3: _____________________________________________________________________

File system:
Boot sector type: -
Boot sector info:

nvme0n1p4: _____________________________________________________________________

File system: ntfs
Boot sector type: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System: Windows 10 or 11
Boot files: /Windows/System32/winload.exe

nvme0n1p5: _____________________________________________________________________

File system: ntfs
Boot sector type: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

nvme1n1p1: _____________________________________________________________________

File system:
Boot sector type: -
Boot sector info:

nvme1n1p2: _____________________________________________________________________

File system:
Boot sector type: -
Boot sector info:

nvme1n1p3: _____________________________________________________________________

File system: ntfs
Boot sector type: NTFS
Boot sector info: According to the info in the boot sector, nvme1n1p3
has 1865322495 sectors, but according to the info from
fdisk, it has 1953492366 sectors.
Operating System:
Boot files:

sda1: __________________________________________________________________________

File system:
Boot sector type: -
Boot sector info:

sda2: __________________________________________________________________________

File system: vfat
Boot sector type: FAT32
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files: /efi/BOOT/bkpbootx64.efi /efi/BOOT/bootx64.efi
/efi/BOOT/fbx64.efi /efi/BOOT/grubx64.efi
/efi/BOOT/mmx64.efi /efi/Kubuntu/grubx64.efi
/efi/Kubuntu/mmx64.efi /efi/Kubuntu/shimx64.efi
/efi/ubuntu/grubx64.efi /efi/ubuntu/mmx64.efi
/efi/ubuntu/shimx64.efi /efi/Kubuntu/grub.cfg
/efi/ubuntu/grub.cfg

sda3: __________________________________________________________________________

File system: swap
Boot sector type: -
Boot sector info:

sda4: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Ubuntu 22.04.5 LTS
Boot files: /boot/grub/grub.cfg /etc/fstab /etc/default/grub

sda5: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System:
Boot files:

sdb1: __________________________________________________________________________

File system:
Boot sector type: -
Boot sector info:

sdb2: __________________________________________________________________________

File system: ntfs
Boot sector type: NTFS
Boot sector info: According to the info in the boot sector, sdb2 has
3519033343 sectors, but according to the info from
fdisk, it has 7814000639 sectors.
Operating System:
Boot files:

sdc1: __________________________________________________________________________

File system: vfat
Boot sector type: MSWIN4.1: FAT32
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files: /boot/grub/grub.cfg /efi/boot/bootx64.efi
/efi/boot/grubx64.efi /efi/boot/mmx64.efi


================================ 2 OS detected =================================

OS#1 (linux): Ubuntu 22.04.5 LTS on sda4
OS#2 (windows): Windows 10 or 11 on nvme0n1p4

================================ Host/Hardware =================================

CPU architecture: 64-bit
Video: GA102 [GeForce RTX 3090] simpledrmdrmfb from NVIDIA Corporation
Live-session OS is Ubuntu 64-bit (Ubuntu 22.04.5 LTS, jammy, x86_64)

===================================== UEFI =====================================

BIOS/UEFI firmware: F35(5.17) from American Megatrends International, LLC.
The firmware is EFI-compatible, and is set in EFI-mode for this live-session.
SecureBoot disabled (confirmed by mokutil).
BootCurrent: 0012
Timeout: 1 seconds
BootOrder: 0012,0011,0001,0000,000F,000B,000D,000E,0010,0013
Boot0000* ubuntu HD(2,GPT,e675fb2d-23f4-4275-8e4e-0f5e0d1e5a56,0x109000,0x31800)/File(\EFI\UBUNTU\SHIMX64.EFI)WINDOWS.........x...B.C.D.O.B.J.E.C.T.=.{.9.d.e.a.8.6.2.c.-.5.c.d.d.-.4.e.7.0.-.a.c.c.1.-.f.3.2.b.3.4.4.d.4.7.9.5.}...a................
Boot0001* ubuntu HD(2,GPT,bd52c86c-2e70-4cfc-8a0b-0e8cd9e2f1cc,0x8000,0xf4000)/File(\EFI\UBUNTU\SHIMX64.EFI)
Boot000B* ST6000DM003-2CY186 BBS(HD,,0x0)..BO
Boot000D* INTEL SSDPEKNW010T8 BBS(HD,,0x0)..BO
Boot000E* Samsung SSD 980 PRO 1TB BBS(HD,,0x0)..BO
Boot000F* PIONEER DVD-RW DVR-212 BBS(CDROM,,0x0)..BO
Boot0010* ST4000DM004-2CV104 BBS(HD,,0x0)..BO
Boot0011* Windows Boot Manager HD(2,GPT,e675fb2d-23f4-4275-8e4e-0f5e0d1e5a56,0x109000,0x31800)/File(\EFI\MICROSOFT\BOOT\BOOTMGFW.EFI)..BO
Boot0012* UEFI: UFD 3.0 Silicon-Power16GPMAP, Partition 1 PciRoot(0x0)/Pci(0x1,0x2)/Pci(0x0,0x0)/Pci(0x8,0x0)/Pci(0x0,0x3)/USB(8,0)/HD(1,MBR,0x28ad1,0x800,0x1d837e0)..BO
Boot0013* UFD 3.0 Silicon-Power16GPMAP BBS(HD,,0x0)..BO

07e25dcaf57c776875f78fa36827c58e nvme0n1p2/Boot/bootx64.efi
1d43d986c265d8c455d020e4a1f28c52 nvme0n1p2/Boot/fbx64.efi
1d260ff1255f189ab621209796ee2fed nvme0n1p2/Boot/mmx64.efi
a1da253696a304dce6b4668b70151c0e nvme0n1p2/ubuntu/grubx64.efi
1d260ff1255f189ab621209796ee2fed nvme0n1p2/ubuntu/mmx64.efi
07e25dcaf57c776875f78fa36827c58e nvme0n1p2/ubuntu/shimx64.efi
62c7a02cbd58c7b7a54f2e776a1880a7 nvme0n1p2/Microsoft/Boot/bootmgfw.efi
a04c74d166128825fc1c64afed71aaac nvme0n1p2/Microsoft/Boot/bootmgr.efi
13bbe79f47b4d57f791e51f5c01f7ac8 nvme0n1p2/Microsoft/Boot/SecureBootRecovery.efi
728124f6ec8e22fbdbe7034812c81b95 sda2/BOOT/bkpbootx64.efi
07e25dcaf57c776875f78fa36827c58e sda2/BOOT/bootx64.efi
1d43d986c265d8c455d020e4a1f28c52 sda2/BOOT/fbx64.efi
ce4cbbb3600d4dcd3914f6e97bbc46f1 sda2/BOOT/grubx64.efi
1d260ff1255f189ab621209796ee2fed sda2/BOOT/mmx64.efi
a1da253696a304dce6b4668b70151c0e sda2/Kubuntu/grubx64.efi
1d260ff1255f189ab621209796ee2fed sda2/Kubuntu/mmx64.efi
07e25dcaf57c776875f78fa36827c58e sda2/Kubuntu/shimx64.efi

============================= Drive/Partition Info =============================

Disks info: ____________________________________________________________________

nvme0n1 : is-GPT, no-BIOSboot, has---ESP, not-usb, not-mmc, has-os, has-win, 2048 sectors * 512 bytes
nvme1n1 : is-GPT, no-BIOSboot, has-noESP, not-usb, not-mmc, no-os, no-wind, 34 sectors * 512 bytes
sda : is-GPT, no-BIOSboot, has---ESP, not-usb, not-mmc, has-os, no-wind, 34 sectors * 512 bytes
sdb : is-GPT, no-BIOSboot, has-noESP, not-usb, not-mmc, no-os, no-wind, 34 sectors * 512 bytes

Partitions info (1/3): _________________________________________________________

nvme0n1p1 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
nvme0n1p2 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
nvme0n1p4 : is-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
nvme0n1p5 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
nvme1n1p3 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
sda2 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
sda4 : is-os, 64, apt-get, signed grub-pc grub-efi , grub2, grub-install, grubenv-ok, update-grub, end-after-100GB
sda5 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
sdb2 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, end-after-100GB
nvme1n1p1 : no-os, 64, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far

Partitions info (2/3): _________________________________________________________

nvme0n1p1 : isnotESP, part-has-no-fstab, no-nt, no-winload, recovery-or-hidden, no-bmgr, notwinboot, ntfs
nvme0n1p2 : is---ESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, vfat
nvme0n1p4 : isnotESP, part-has-no-fstab, no-nt, haswinload, no-recov-nor-hid, no-bmgr, notwinboot, ntfs
nvme0n1p5 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ntfs
nvme1n1p3 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ntfs
sda2 : is---ESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, vfat
sda4 : isnotESP, fstab-has-goodEFI, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ext4
sda5 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ext4
sdb2 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot, ntfs
nvme1n1p1 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot,

Partitions info (3/3): _________________________________________________________

nvme0n1p1 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme0n1
nvme0n1p2 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme0n1
nvme0n1p4 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme0n1
nvme0n1p5 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme0n1
nvme1n1p3 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme1n1
sda2 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, sda
sda4 : not--sepboot, with-boot, fstab-without-boot, not-sep-usr, with--usr, fstab-without-usr, std-grub.d, sda
sda5 : maybesepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, sda
sdb2 : not--sepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, sdb
nvme1n1p1 : maybesepboot, no---boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, no--grub.d, nvme1n1

fdisk -l (filtered): ___________________________________________________________

Disk nvme0n1: 953.87 GiB, 1024209543168 bytes, 2000409264 sectors
Disk identifier: BF28BE10-6823-4473-BEA8-0C6A982FD07D
Start End Sectors Size Type
nvme0n1p1 2048 1085439 1083392 529M Windows recovery environment
nvme0n1p2 1085440 1288191 202752 99M EFI System
nvme0n1p3 1288192 1320959 32768 16M Microsoft reserved
nvme0n1p4 1320960 1590808575 1589487616 757.9G Microsoft basic data
nvme0n1p5 1590808576 2000406527 409597952 195.3G Microsoft basic data
Disk nvme1n1: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
Disk identifier: A15E82CA-117E-43C6-84AD-5C7D59F3DD3E
Start End Sectors Size Type
nvme1n1p1 34 2081 2048 1M Microsoft LDM metadata
nvme1n1p2 2082 32767 30686 15M Microsoft reserved
nvme1n1p3 32768 1953525134 1953492367 931.5G Microsoft LDM data
Disk sda: 5.46 TiB, 6001175126016 bytes, 11721045168 sectors
Disk identifier: 9698E43A-51A4-4E17-8AE2-82BF710BCA3A
Start End Sectors Size Type
sda1 34 32767 32734 16M Microsoft reserved
sda2 32768 1032191 999424 488M EFI System
sda3 1032192 126031871 124999680 59.6G Linux swap
sda4 126031872 1102594047 976562176 465.7G Linux filesystem
sda5 1102594048 7246594047 6144000000 2.9T Linux filesystem
Disk sdb: 3.64 TiB, 4000787030016 bytes, 7814037168 sectors
Disk identifier: 57D96C7D-C89E-4F26-ACD6-09ABE0B1F8E9
Start End Sectors Size Type
sdb1 34 32767 32734 16M Microsoft reserved
sdb2 32768 7814033407 7814000640 3.6T Microsoft basic data
Disk sdc: 14.76 GiB, 15846080512 bytes, 30949376 sectors
Disk identifier: 0x00028ad1
Boot Start End Sectors Size Id Type
sdc1 * 2048 30949343 30947296 14.8G c W95 FAT32 (LBA)

parted -lm (filtered): _________________________________________________________

sda:6001GB:scsi:512:4096:gpt:ATA ST6000DM003-2CY1:;
1:17.4kB:16.8MB:16.8MB::Microsoft reserved partition:msftres;
2:16.8MB:528MB:512MB:fat32::boot, esp;
3:528MB:64.5GB:64.0GB:linux-swap(v1)::swap;
4:64.5GB:565GB:500GB:ext4::;
5:565GB:3710GB:3146GB:ext4::legacy_boot;
sdb:4001GB:scsi:512:4096:gpt:ATA ST4000DM004-2CV1:;
1:17.4kB:16.8MB:16.8MB::Microsoft reserved partition:msftres;
2:16.8MB:4001GB:4001GB:ntfs:Basic data partition:msftdata;
sdc:15.8GB:scsi:512:512:msdos:UFD 3.0 Silicon-Power16G:;
1:1049kB:15.8GB:15.8GB:fat32::boot, lba;
nvme0n1:1024GB:nvme:512:512:gpt:INTEL SSDPEKNW010T8:;
1:1049kB:556MB:555MB:ntfs:Basic data partition:hidden, diag;
2:556MB:660MB:104MB:fat32:EFI system partition:boot, esp;
3:660MB:676MB:16.8MB::Microsoft reserved partition:msftres;
4:676MB:814GB:814GB:ntfs:Basic data partition:msftdata;
5:814GB:1024GB:210GB:ntfs:Basic data partition:msftdata;
nvme1n1:1000GB:nvme:512:512:gpt:Samsung SSD 980 PRO 1TB:;
1:17.4kB:1066kB:1049kB::LDM metadata partition:;
2:1066kB:16.8MB:15.7MB::Microsoft reserved partition:msftres;
3:16.8MB:1000GB:1000GB:ntfs:LDM data partition:;

Free space >10MiB: ______________________________________________________________

sda: 3538376MiB:5723167MiB:2184791MiB

blkid (filtered): ______________________________________________________________

NAME FSTYPE UUID PARTUUID LABEL PARTLABEL
sda
├─sda1 d1520670-0e55-40b1-84da-833207f9c3eb Microsoft reserved partition
├─sda2 vfat 6984-2433 bd52c86c-2e70-4cfc-8a0b-0e8cd9e2f1cc
├─sda3 swap 928feb31-5e47-4fb2-b1de-f02acd097349 9cc867ce-020b-47b4-a0b4-0b4c94e2921d
├─sda4 ext4 78c23be8-bca0-4de3-970d-4957255257f5 c1c06065-0e3f-449d-b942-2fe1cd476618 local1
└─sda5 ext4 2a388419-91ed-47e8-b200-5fcd52b8927a 327aafbd-e7d1-1343-93e1-bc45524270ab tlg
sdb
├─sdb1 c020a18b-91b9-495d-b48a-60137726677f Microsoft reserved partition
└─sdb2 ntfs B0C2D190C2D15AE4 20937c6c-0acb-4608-841d-a56d6b4cdb25 BronRenders Basic data partition
sdc
└─sdc1 vfat 8032-AF33 00028ad1-01 KUBUNTU 22_
nvme0n1
├─nvme0n1p1 ntfs CC1C7DD01C7DB654 5e1247be-1452-4abf-9396-38ae86b8a405 Recovery Basic data partition
├─nvme0n1p2 vfat 4E7E-2861 e675fb2d-23f4-4275-8e4e-0f5e0d1e5a56 EFI system partition
├─nvme0n1p3 7bb93195-309c-43d2-803d-11aea62a8bb2 Microsoft reserved partition
├─nvme0n1p4 ntfs 82EC815DEC814BFB fa0a29e7-4683-48a1-bcfd-a789a9c8a808 Basic data partition
└─nvme0n1p5 ntfs 86284D87284D76E9 9ced67d4-78a1-4e98-b0c7-65fbcefd60a0 TLG Basic data partition
nvme1n1
├─nvme1n1p1 0c27cf8e-a155-11ed-9b82-b42e99d1d71f LDM metadata partition
├─nvme1n1p2 5bd9c0aa-e526-400e-a7cf-4fbde3cbeed7 Microsoft reserved partition
└─nvme1n1p3 ntfs E026E8F226E8CA9C 0c27cf93-a155-11ed-9b82-b42e99d1d71f BRON LDM data partition

Mount points (filtered): _______________________________________________________

Avail Use% Mounted on
/dev/nvme0n1p1 62.2M 88% /mnt/boot-sav/nvme0n1p1
/dev/nvme0n1p2 63.3M 33% /mnt/boot-sav/nvme0n1p2
/dev/nvme0n1p4 135.6G 82% /mnt/boot-sav/nvme0n1p4
/dev/nvme0n1p5 22.9G 88% /mnt/boot-sav/nvme0n1p5
/dev/nvme1n1p3 396.5G 55% /mnt/boot-sav/nvme1n1p3
/dev/sda2 474.1M 3% /mnt/boot-sav/sda2
/dev/sda4 237.8G 43% /mnt/boot-sav/sda4
/dev/sda5 2.5T 6% /mnt/boot-sav/sda5
/dev/sdb2 1T 72% /mnt/boot-sav/sdb2
/dev/sdc1 10.8G 27% /cdrom
efivarfs 95.8K 21% /sys/firmware/efi/efivars

Mount options (filtered): ______________________________________________________

/dev/nvme0n1p1 fuseblk rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
/dev/nvme0n1p2 vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
/dev/nvme0n1p4 fuseblk rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
/dev/nvme0n1p5 fuseblk rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
/dev/nvme1n1p3 fuseblk rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
/dev/sda2 vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
/dev/sda4 ext4 rw,relatime
/dev/sda5 ext4 rw,relatime
/dev/sdb2 fuseblk rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
/dev/sdc1 vfat ro,noatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro

=================== nvme0n1p2/efi/ubuntu/grub.cfg (filtered) ===================

search.fs_uuid 78c23be8-bca0-4de3-970d-4957255257f5 root hd0,gpt4
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

===================== sda2/efi/Kubuntu/grub.cfg (filtered) =====================

search.fs_uuid 78c23be8-bca0-4de3-970d-4957255257f5 root hd0,gpt4
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

===================== sda2/efi/ubuntu/grub.cfg (filtered) ======================

search.fs_uuid 78c23be8-bca0-4de3-970d-4957255257f5 root hd0,gpt4
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

====================== sda4/boot/grub/grub.cfg (filtered) ======================

Ubuntu 78c23be8-bca0-4de3-970d-4957255257f5
### END /etc/grub.d/30_os-prober ###
UEFI Firmware Settings uefi-firmware
### END /etc/grub.d/30_uefi-firmware ###

========================== sda4/etc/fstab (filtered) ===========================

# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sda4 during installation
UUID=78c23be8-bca0-4de3-970d-4957255257f5 / ext4 errors=remount-ro 0 1
# /boot/efi was on /dev/nvme0n1p2 during installation
# swap was on /dev/sda3 during installation
UUID=928feb31-5e47-4fb2-b1de-f02acd097349 none swap sw 0 0
UUID=6984-2433 /boot/efi vfat defaults 0 1
UUID=2a388419-91ed-47e8-b200-5fcd52b8927a /tlg ext4 defaults 0 0

======================= sda4/etc/default/grub (filtered) =======================

GRUB_DEFAULT=2
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset"
GRUB_CMDLINE_LINUX=""

==================== sda4: Location of files loaded by Grub ====================

GiB - GB File Fragment(s)
388.668369293 = 417.329483776 boot/grub/grub.cfg 1
70.560699463 = 75.763974144 boot/vmlinuz 2
238.435703278 = 256.018386944 boot/vmlinuz-5.15.0-119-generic 2
70.560699463 = 75.763974144 boot/vmlinuz-5.15.0-121-generic 2
238.435703278 = 256.018386944 boot/vmlinuz.old 2
68.302230835 = 73.338961920 boot/initrd.img 7
471.419414520 = 506.182742016 boot/initrd.img-5.15.0-119-generic 3
68.302230835 = 73.338961920 boot/initrd.img-5.15.0-121-generic 7
471.419414520 = 506.182742016 boot/initrd.img.old 3

===================== sda4: ls -l /etc/grub.d/ (filtered) ======================

-rwxr-xr-x 1 root root 18683 Apr 15 2022 10_linux
-rwxr-xr-x 1 root root 43031 Mar 30 2021 10_linux_zfs
-rwxr-xr-x 1 root root 14387 Dec 18 2022 20_linux_xen
-rwxr-xr-x 1 root root 13369 Apr 15 2022 30_os-prober
-rwxr-xr-x 1 root root 1372 Apr 15 2022 30_uefi-firmware
-rwxr-xr-x 1 root root 700 Feb 19 2022 35_fwupd
-rwxr-xr-x 1 root root 214 Mar 30 2021 40_custom
-rwxr-xr-x 1 root root 215 Apr 15 2022 41_custom

====================== sdc1/boot/grub/grub.cfg (filtered) ======================

Try or Install Kubuntu
Kubuntu (safe graphics)
OEM install (for manufacturers)
Boot from next volume
UEFI Firmware Settings
Test memory

==================== sdc1: Location of files loaded by Grub ====================

GiB - GB File Fragment(s)
?? = ?? boot/grub/grub.cfg 1



Suggested repair: ______________________________________________________________

The default repair of the Boot-Repair utility would reinstall the grub-efi of
sda4,
using the following options: sda2/boot/efi
Additional repair would be performed: unhide-bootmenu-10s use-standard-efi-file restore-efi-backups

Final advice in case of suggested repair: ______________________________________

Please do not forget to make your UEFI firmware boot on the Ubuntu 22.04.5 LTS entry (sda2/efi/****/grub****.efi (**** will be updated in the final message) file) !
If your computer reboots directly into Windows, try to change the boot order in your UEFI firmware.
If your UEFI firmware does not allow to change the boot order, change the default boot entry of the Windows bootloader.
For example you can boot into Windows, then type the following command in an admin command prompt:
bcdedit /set {bootmgr} path \EFI\****\grub****.efi (**** will be updated in the final message)
​

[Qqmike]

Let me leave my impression here, quickly, as I have an appointment to get to.
The bottom line looks reasonable and safe:

The default repair of the Boot-Repair utility would reinstall the grub-efi of sda4,
using the following options: sda2/boot/efi
Please do not forget to make your UEFI firmware boot on the Ubuntu 22.04.5 LTS entry (sda2/efi/****/grub****.efi (**** will be updated in the final message) file)
If your computer reboots directly into Windows, try to change the boot order in your UEFI firmware.

Your Kubuntu is on sda4, its ESP partition is clearly sda2.
Good chance that your GRUB is just all messed up, starting with /usr/lib/grub files -- your basic GRUB files.
You are not messing with Windows as you do this --
you are only messing with Kubuntu's GRUB ... it seems safe, AND probably necessary in ANY case.

Note the advice after it re-installs GRUB-efi: make sure your UEFI firmware boots on the sda2 ESP GRUB from Kubuntu.
efibootmgr:
is a command to see your boot order (and boot variables)
the -o option lets you change the boot order ... and so on.
FIRST, if it were me, I would allow Boot Repair to reinstall my basic, necessary GRUB files.
Then re-boot to see what happens.

That's my quick take on this.
Some of this output seems complicated.
Wondering what all you have in your system!