I have a Windows 10 computer that I originally added Ubuntu and it was dual booting just fine. Then I decided to try to add another partition and it was for Manjaro (if that matters). All three seemed to work fine. Then because I just can't keep my hands off things, I replaced Ubuntu with Mint.
What happened is windows and mint boot just fine from Mint's grub. However if the Manjaro wont boot from the Mint grub menu.
But if I restart and go to bios (or efi) menu I can choose Manjaro and the bios runs the Manjaro grub.
I would like to try to get this under control but I am afraid of bricking the whole darn thing. Don't ask me why I know that can happen.
I have enclosed a screen shot of gparted.

Attached Thumbnails

 

Is the Manjaro install on sda8?
You've updated Grub on Mint so that you see an entry for Manjaro in the Mint Grub menu, correct?
So what happens when you select Manjaro from the menu? Blinking cursor, black screen, etc.??
Have you checked the grub.cfg file for the Manjaro entry to see if the UUID in that entry is correct?

In your situation where all 3 systems were booting correctly from Grub, making a backup copy of at least the menuentries from that grub.cfg file would be very useful now. Something to consider in the future, particularly if you plan to be changing distros.

If you don't resolve this, you might get the boot repair software, use the 2nd option described on the page and use the Create BootInfo Summary option only and post the link you get when it finishes here. Outputs a lot of potentially useful information.

https://help.ubuntu.com/community/Boot-Repair

Been a couple of years since I looked at Manjaro, but it seems they are pissing off more than a few people - have a read of this recent thread.

Arrrgh - seems I misread. What does "efibootmgr -v" show from Mint ?.

Yes I do see the Manjaro entry on Mint's grub. If I choose Manjaro the computer just sits on what looks like the bios start. No blinks or anything. I have to turn off the machine and restart to get back to Mint's menu. Which btw is what starts by default. If I interrupt the boot and go into bios, I can choose Manjaro which leads to Manjaro's grub menu. Manjaro will then start just fine.
I would be happy to just dump Manjaro (which is on sda8) and stay with Windows and Mint on sda7. Then I would like to incorparate sda7 and sda8.
I am hesitant to mess around with grub because I don't know enough to get out of trouble. I probably need to learn more about uefi and efi. But grub scares me because I can tell you that I have definitely done damage messing around with it.
Perhaps I should try slackware with lilo which never caused me a problem before.

I have no idea what any of those extra partitions are on the disk. I didn't put them there, they were all added by either calamares or ubiqity, I think.

Here is a copy of the boot-repair message:

boot-repair-4ppa125 [20210319_1030]

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

=> No boot loader is installed in the MBR of /dev/sda.
=> No boot loader is installed in the MBR of /dev/sdc.

sda1: __________________________________________________________________________

File system: vfat
Boot sector type: Windows 8/2012: 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/Manjaro/grubx64.efi
/efi/ubuntu/grubx64.efi /efi/ubuntu/mmx64.efi
/efi/ubuntu/shimx64.efi /efi/ubuntu/grub.cfg
/efi/dell/SOS/bootmgfw.efi /efi/dell/SOS/bootmgr.efi
/efi/dell/SOS/bootx64.efi /efi/dell/SOS/memtest.efi
/efi/Microsoft/Boot/bootmgfw.efi
/efi/Microsoft/Boot/bootmgr.efi
/efi/Microsoft/Boot/memtest.efi /bootmgr /boot/bcd

sda2: __________________________________________________________________________

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

sda3: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 8/2012: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System: Windows 8 or 10
Boot files: /Windows/System32/winload.exe

sda4: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 8/2012: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

sda5: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 8/2012: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

sda6: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 8/2012: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

sda7: __________________________________________________________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Linux Mint 20.1
Boot files: /boot/grub/grub.cfg /etc/fstab /etc/default/grub

sda8: __________________________________________________________________________

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

sdc1: __________________________________________________________________________

File system: vfat
Boot sector type: Unknown
Boot sector info: According to the info in the boot sector, sdc1 starts
at sector 0. But according to the info from fdisk,
sdc1 starts at sector 40.
Operating System:
Boot files:

sdc2: __________________________________________________________________________

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

sdc3: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows 8/2012: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System:
Boot files:

sdb: ___________________________________________________________________________

File system: iso9660
Boot sector type: Unknown
Boot sector info:
Mounting failed: mount: /mnt/BootInfo/FD/sdb: /dev/sdb already mounted or mount point busy.


================================ 3 OS detected =================================

OS#1: The OS now in use - Linux Mint 20.1 CurrentSession on sda7
OS#2: Manjaro Linux (20.2.1) on sda8
OS#3: Windows 8 or 10 on sda3

============================ Architecture/Host Info ============================

CPU architecture: 64-bit
BOOT_IMAGE of the installed session in use:
/boot/vmlinuz-5.4.0-67-generic root=UUID=e34ba30b-dc6d-417b-937a-1f2d772024ca ro quiet splash


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

BIOS is EFI-compatible, and is setup in EFI-mode for this installed-session.
No EFI in dmseg.
SecureBoot disabled.

efibootmgr -v
BootCurrent: 0003
Timeout: 1 seconds
BootOrder: 0003,0004,0000,0001,0002
Boot0000* Windows Boot Manager HD(1,GPT,7393f19c-5450-477f-aa79-e1793086324d,0x800,0x145000)/File(\EFI\Microsoft\Boot\bootmgfw.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.}....................
Boot0001* Onboard NIC (IPV4) PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(e4b97ae9f48a,0)/IPv4(0.0.0.00.0.0.0,0,0)..BO
Boot0002* Onboard NIC (IPV6) PciRoot(0x0)/Pci(0x1c,0x0)/Pci(0x0,0x0)/MAC(e4b97ae9f48a,0)/IPv6([::]:<->[::]:,0,0)..BO
Boot0003* ubuntu HD(1,GPT,7393f19c-5450-477f-aa79-e1793086324d,0x800,0x145000)/File(\EFI\ubuntu\shimx64.efi)
Boot0004* Manjaro HD(1,GPT,7393f19c-5450-477f-aa79-e1793086324d,0x800,0x145000)/File(\EFI\Manjaro\grubx64.efi)

78415fb8fb9b909f8029858113f1335f sda1/Boot/bootx64.efi
2895d47544fd587b26c7e29be1295c27 sda1/Boot/fbx64.efi
dc3c47be2f78a78e5e57d097ae6c5c84 sda1/Boot/mmx64.efi
171bd936d5c87d73dfb18b08131d04f7 sda1/Manjaro/grubx64.efi
957dc7e5f72c1d7393bf7850df5db2db sda1/ubuntu/grubx64.efi
dc3c47be2f78a78e5e57d097ae6c5c84 sda1/ubuntu/mmx64.efi
78415fb8fb9b909f8029858113f1335f sda1/ubuntu/shimx64.efi
b6687ab259a2e54a3efb66e085786ca6 sda1/dell/SOS/bootmgfw.efi
ce41278a73e6463ef40afbf717f18249 sda1/dell/SOS/bootmgr.efi
b6687ab259a2e54a3efb66e085786ca6 sda1/dell/SOS/bootx64.efi
3c080490d0eb8fdb738f298c3e44b3e0 sda1/Microsoft/Boot/bootmgfw.efi
da7c9088c9d0bff4ac469abdfc8f540e sda1/Microsoft/Boot/bootmgr.efi


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

Disks info: ____________________________________________________________________

sda : is-GPT, no-BIOSboot, has---ESP, not-usb, not-mmc, has-os, 2048 sectors * 512 bytes
sdc : is-GPT, no-BIOSboot, has---ESP, usb-disk, not-mmc, no-os, 40 sectors * 512 bytes

Partitions info (1/3): _________________________________________________________

sda7 : is-os, 64, apt-get, signed grub-pc grub-efi , grub2, grub-install, grubenv-ok, update-grub, farbios
sda1 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
sda3 : is-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios
sda4 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios
sda5 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios
sda6 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios
sda8 : is-os, 64, pacman, no-docgrub, grub2, grub-install, grubenv-ng, update-grub, farbios
sdc1 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, not-far
sdc2 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios
sdc3 : no-os, 32, nopakmgr, no-docgrub, nogrub, nogrubinstall, no-grubenv, noupdategrub, farbios

Partitions info (2/3): _________________________________________________________

sda7 : isnotESP, fstab-has-goodEFI, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot
sda1 : is---ESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, bootmgr, is-winboot
sda3 : isnotESP, part-has-no-fstab, no-nt, haswinload, no-recov-nor-hid, no-bmgr, notwinboot
sda4 : isnotESP, part-has-no-fstab, no-nt, no-winload, recovery-or-hidden, no-bmgr, notwinboot
sda5 : isnotESP, part-has-no-fstab, no-nt, no-winload, recovery-or-hidden, no-bmgr, notwinboot
sda6 : isnotESP, part-has-no-fstab, no-nt, no-winload, recovery-or-hidden, no-bmgr, notwinboot
sda8 : isnotESP, fstab-has-goodEFI, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot
sdc1 : is---ESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot
sdc2 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot
sdc3 : isnotESP, part-has-no-fstab, no-nt, no-winload, no-recov-nor-hid, no-bmgr, notwinboot

Partitions info (3/3): _________________________________________________________

sda7 : not-sepboot, with-boot, fstab-without-boot, not-sep-usr, with--usr, fstab-without-usr, std-grub.d, sda
sda1 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sda
sda3 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sda
sda4 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sda
sda5 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sda
sda6 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sda
sda8 : not-sepboot, with-boot, fstab-without-boot, not-sep-usr, with--usr, fstab-without-usr, std-grub.d, sda
sdc1 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sdc
sdc2 : maybesepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sdc
sdc3 : not-sepboot, no-boot, part-has-no-fstab, not-sep-usr, no---usr, part-has-no-fstab, std-grub.d, sdc

fdisk -l (filtered): ___________________________________________________________

Disk sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk identifier: 14818A06-C0FB-4819-9A1F-38676671FFDD
Start End Sectors Size Type
sda1 2048 1333247 1331200 650M EFI System
sda2 1333248 1595391 262144 128M Microsoft reserved
sda3 1595392 980052207 978456816 466.6G Microsoft basic data
sda4 1927772160 1929799679 2027520 990M Windows recovery environment
sda5 1929799680 1951154175 21354496 10.2G Windows recovery environment
sda6 1951154176 1953501183 2347008 1.1G Windows recovery environment
sda7 980054016 1453913088 473859073 226G Linux filesystem
sda8 1453913090 1927772159 473859070 226G Linux filesystem
Partition table entries are not in disk order.
Disk sdc: 149.5 GiB, 160041885696 bytes, 312581808 sectors
Disk identifier: 54C91E30-6841-4AEE-A139-338E5C55C3BC
Start End Sectors Size Type
sdc1 40 409639 409600 200M EFI System
sdc2 409640 312319623 311909984 148.7G Apple HFS/HFS+
sdc3 312320000 312580095 260096 127M Microsoft basic data
Disk sdb: 7.47 GiB, 8004304896 bytes, 15633408 sectors
Disk identifier: 0x38b1c112
Boot Start End Sectors Size Id Type
sdb1 * 0 5619583 5619584 2.7G 0 Empty
sdb2 1700 9699 8000 3.9M ef EFI (FAT-12/16/32)
sdb3 5619712 15633407 10013696 4.8G 83 Linux

parted -lm (filtered): _________________________________________________________

sda:1000GB:scsi:512:4096:gpt:ATA ST1000LM035-1RK1:;
1:1049kB:683MB:682MB:fat32:EFI system partition:boot, esp;
2:683MB:817MB:134MB::Microsoft reserved partition:msftres;
3:817MB:502GB:501GB:ntfs:Basic data partition:msftdata;
7:502GB:744GB:243GB:ext4::;
8:744GB:987GB:243GB:ext4::;
4:987GB:988GB:1038MB:ntfs::diag;
5:988GB:999GB:10.9GB:ntfs::diag;
6:999GB:1000GB:1202MB:ntfs::hidden, diag;
sdb:8004MB:scsi:512:512:unknown:SanDisk Cruzer:;
sdc:160GB:scsi:512:512:gpt:WDC WD16 00BEVE-22UYT0:;
1:20.5kB:210MB:210MB:fat32:EFI System Partition:boot, esp;
2:210MB:160GB:160GB:hfs+:time_mach:;
3:160GB:160GB:133MB:ntfs:Basic data partition:msftdata;

blkid (filtered): ______________________________________________________________

NAME FSTYPE UUID PARTUUID LABEL PARTLABEL
sda
├─sda1 vfat 1231-4D67 7393f19c-5450-477f-aa79-e1793086324d ESP EFI system partition
├─sda2 1401c217-ff40-46c2-920d-50051f5f9530 Microsoft reserved partition
├─sda3 ntfs 9892C23B92C21D9E 7b371ff1-6bd5-4e29-8810-05e4741c43ea OS Basic data partition
├─sda4 ntfs 7CE8CA58E8CA1076 508f7d3c-477d-42ec-9c5c-518d174645b5 WINRETOOLS
├─sda5 ntfs 2026AF8826AF5D92 5f0e11cd-6fc1-41b9-9aa5-2f2bfc346324 Image
├─sda6 ntfs 00ACA14DACA13E52 734dfa68-9e7d-4fb2-9cf4-aacea4b45e98 DELLSUPPORT
├─sda7 ext4 e34ba30b-dc6d-417b-937a-1f2d772024ca 61523506-ef53-4e5e-8787-1b234b7ec145
└─sda8 ext4 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9 b755da31-e903-c549-8295-5251e2ec95b2
sdb iso9660 2021-02-09-19-06-26-00 Ubuntu 20.04.2.0 LTS amd64
├─sdb1 iso9660 2021-02-09-19-06-26-00 38b1c112-01 Ubuntu 20.04.2.0 LTS amd64
├─sdb2 vfat 54C5-9C6C 38b1c112-02
└─sdb3 ext4 712ec86b-eb52-4001-baaa-ee715c9b45a1 38b1c112-03 writable
sdc
├─sdc1 vfat 70D6-1701 79bb9b3b-ce23-407a-9cb3-c85b2cc019d5 EFI EFI System Partition
├─sdc2 hfsplus 66d43c26-aa86-3e0b-b04c-d70b2d753ca9 5d1f301d-222d-4215-b958-842e7d3f5b8f time_mach time_mach
└─sdc3 ntfs C0EEF091EEF080C8 b4351435-2892-4f42-8ce7-c0d754517de7 New Volume Basic data partition

df (filtered): _________________________________________________________________

Avail Use% Mounted on
sda3 444.8G 5% /mnt/boot-sav/sda3
sda4 146M 85% /mnt/boot-sav/sda4
sda5 1.9G 81% /mnt/boot-sav/sda5
sda6 293.5M 74% /mnt/boot-sav/sda6
sda7 155.7G 25% /
sda7 155.7G 25% /run/timeshift/backup
sda8 198.2G 5% /mnt/boot-sav/sda8
sdb1 0 100% /media/bwg/Ubuntu 20.04.2.0 LTS amd641
sdb3 4.4G 0% /media/bwg/writable1
sdc1 183M 7% /mnt/boot-sav/sdc1
sdc2 9G 94% /media/bwg/time_mach
sdc3 116.9M 8% /mnt/boot-sav/sdc3

Mount options: __________________________________________________________________

sda3 rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
sda4 rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
sda5 rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
sda6 rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096
sda7 rw,relatime,errors=remount-ro
sda7 rw,relatime,errors=remount-ro
sda8 rw,relatime
sdb1 ro,nosuid,nodev,relatime,nojoliet,check=s,map=n,blocksize=2048,uid=1000,gid=1000,dmode=500,fmode=400
sdb3 rw,nosuid,nodev,relatime
sdc1 rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro
sdc2 ro,nosuid,nodev,relatime,umask=22,uid=1000,gid=1000,nls=utf8
sdc3 rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096

===================== sda1/efi/ubuntu/grub.cfg (filtered) ======================

search.fs_uuid e34ba30b-dc6d-417b-937a-1f2d772024ca root hd0,gpt7
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg

====================== sda7/boot/grub/grub.cfg (filtered) ======================

Linux Mint 20.1 Cinnamon e34ba30b-dc6d-417b-937a-1f2d772024ca
Linux Mint 20.1 Cinnamon, with Linux 5.4.0-67-generic e34ba30b-dc6d-417b-937a-1f2d772024ca
Linux Mint 20.1 Cinnamon, with Linux 5.4.0-66-generic e34ba30b-dc6d-417b-937a-1f2d772024ca
Linux Mint 20.1 Cinnamon, with Linux 5.4.0-58-generic e34ba30b-dc6d-417b-937a-1f2d772024ca
Windows Boot Manager (on sda1) osprober-efi-1231-4D67
Manjaro Linux (20.2.1) (on sda8) 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Manjaro Linux (on sda8) 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Manjaro Linux (Kernel 5.9.16-1-MANJARO x64) (on sda8) 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Manjaro Linux (Kernel 5.9.16-1-MANJARO x64 - fallback initramfs) (on sda8) 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
### END /etc/grub.d/30_os-prober ###
UEFI Firmware Settings uefi-firmware
### END /etc/grub.d/30_uefi-firmware ###

========================== sda7/etc/fstab (filtered) ===========================

# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sda7 during installation
UUID=e34ba30b-dc6d-417b-937a-1f2d772024ca / ext4 errors=remount-ro 0 1
# /boot/efi was on /dev/sda1 during installation
UUID=1231-4D67 /boot/efi vfat umask=0077 0 1
/swapfile none swap sw 0 0

======================= sda7/etc/default/grub (filtered) =======================

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

==================== sda7: Location of files loaded by Grub ====================

GiB - GB File Fragment(s)
674.118125916 = 723.828826112 boot/grub/grub.cfg 1
619.266807556 = 664.932671488 boot/vmlinuz 2
471.602676392 = 506.379517952 boot/vmlinuz-5.4.0-58-generic 1
675.766746521 = 725.599019008 boot/vmlinuz-5.4.0-66-generic 1
619.266807556 = 664.932671488 boot/vmlinuz-5.4.0-67-generic 2
675.766746521 = 725.599019008 boot/vmlinuz.old 1
675.205146790 = 724.996005888 boot/initrd.img 6
685.968093872 = 736.552632320 boot/initrd.img-5.4.0-58-generic 5
688.954730988 = 739.759509504 boot/initrd.img-5.4.0-66-generic 12
675.205146790 = 724.996005888 boot/initrd.img-5.4.0-67-generic 6
688.954730988 = 739.759509504 boot/initrd.img.old 12

===================== sda7: ls -l /etc/grub.d/ (filtered) ======================

-rwxr-xr-x 1 root root 17622 Nov 12 18:15 10_linux
-rwxr-xr-x 1 root root 42359 Nov 12 18:15 10_linux_zfs
-rwxr-xr-x 1 root root 12894 Nov 12 18:15 20_linux_xen
-rwxr-xr-x 1 root root 12059 Nov 12 18:15 30_os-prober
-rwxr-xr-x 1 root root 1424 Nov 12 18:15 30_uefi-firmware
-rwxr-xr-x 1 root root 214 Nov 12 18:15 40_custom
-rwxr-xr-x 1 root root 216 Nov 12 18:15 41_custom

====================== sda8/boot/grub/grub.cfg (filtered) ======================

Manjaro Linux 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Manjaro Linux (Kernel: 5.9.16-1-MANJARO x64) 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Manjaro Linux (Kernel: 5.9.16-1-MANJARO x64 - fallback initramfs) gnulinux-5.9.16-1-MANJARO x64-fallback-0278b3bc-29f3-4e63-b2a2-ad71c46f67d9
Windows Boot Manager (on sda1) osprober-efi-1231-4D67
Ubuntu 20.10 (20.10) (on sda7) b480433f-c21b-4588-a295-bced0fba7282
Ubuntu (on sda7) b480433f-c21b-4588-a295-bced0fba7282
Ubuntu, with Linux 5.8.0-44-generic (on sda7) b480433f-c21b-4588-a295-bced0fba7282
Ubuntu, with Linux 5.8.0-43-generic (on sda7) b480433f-c21b-4588-a295-bced0fba7282
Ubuntu, with Linux 5.8.0-41-generic (on sda7) b480433f-c21b-4588-a295-bced0fba7282
### END /etc/grub.d/30_os-prober ###
UEFI Firmware Settings uefi-firmware
### END /etc/grub.d/30_uefi-firmware ###

========================== sda8/etc/fstab (filtered) ===========================

# <file system> <mount point> <type> <options> <dump> <pass>
UUID=1231-4D67 /boot/efi vfat umask=0077 0 2
UUID=0278b3bc-29f3-4e63-b2a2-ad71c46f67d9 / ext4 defaults,noatime 0 1

======================= sda8/etc/default/grub (filtered) =======================

GRUB_DEFAULT=saved
GRUB_TIMEOUT=5
GRUB_TIMEOUT_STYLE=hidden
GRUB_DISTRIBUTOR="Manjaro"
GRUB_CMDLINE_LINUX_DEFAULT="quiet udev.log_priority=3"
GRUB_CMDLINE_LINUX=""
GRUB_SAVEDEFAULT=true
GRUB_PRELOAD_MODULES="part_gpt part_msdos"
GRUB_TERMINAL_INPUT=console
GRUB_GFXMODE=auto
GRUB_GFXPAYLOAD_LINUX=keep
GRUB_DISABLE_RECOVERY=true
GRUB_COLOR_NORMAL="light-gray/black"
GRUB_COLOR_HIGHLIGHT="green/black"
GRUB_THEME="/usr/share/grub/themes/manjaro/theme.txt"
GRUB_ROOT_FS_RO=true

==================== sda8: Location of files loaded by Grub ====================

GiB - GB File Fragment(s)
771.422707558 = 828.308825088 boot/grub/grub.cfg 1
693.416501045 = 744.550298624 boot/vmlinuz-5.9-x86_64 2
700.510048866 = 752.166937600 boot/initramfs-5.9-x86_64-fallback.img 1
700.271100044 = 751.910368256 boot/initramfs-5.9-x86_64.img 1

===================== sda8: ls -l /etc/grub.d/ (filtered) ======================

-rwxr-xr-x 1 root root 12776 Feb 10 07:10 10_linux
-rwxr-xr-x 1 root root 13327 Feb 10 07:10 20_linux_xen
-rwxr-xr-x 1 root root 12118 Feb 10 07:10 30_os-prober
-rwxr-xr-x 1 root root 1372 Feb 10 07:10 30_uefi-firmware
-rwxr-xr-x 1 root root 214 Feb 10 07:10 40_custom
-rwxr-xr-x 1 root root 215 Feb 10 07:10 41_custom
-rwxr-xr-x 1 root root 1219 May 16 2020 60_memtest86+


======================== Unknown MBRs/Boot Sectors/etc =========================

Unknown BootLoader on sdc1

00000000 eb 58 90 42 53 44 20 20 34 2e 34 00 02 01 20 00 |.X.BSD 4.4... .|
00000010 02 00 00 00 00 f0 00 00 20 00 10 00 00 00 00 00 |........ .......|
00000020 00 40 06 00 4f 0c 00 00 00 00 00 00 02 00 00 00 |.@..O...........|
00000030 01 00 06 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000040 00 01 29 01 17 d6 70 45 46 49 20 20 20 20 20 20 |..)...pEFI |
00000050 20 20 46 41 54 33 32 20 20 20 fa 31 c0 8e d0 bc | FAT32 .1....|
00000060 00 7c fb 8e d8 e8 00 00 5e 83 c6 19 bb 07 00 fc |.|......^.......|
00000070 ac 84 c0 74 06 b4 0e cd 10 eb f5 30 e4 cd 16 cd |...t.......0....|
00000080 19 0d 0a 4e 6f 6e 2d 73 79 73 74 65 6d 20 64 69 |...Non-system di|
00000090 73 6b 0d 0a 50 72 65 73 73 20 61 6e 79 20 6b 65 |sk..Press any ke|
000000a0 79 20 74 6f 20 72 65 62 6f 6f 74 0d 0a 00 00 00 |y to reboot.....|
000000b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200

Unknown BootLoader on sdb

00000000 45 52 08 00 00 00 90 90 00 00 00 00 00 00 00 00 |ER..............|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020 33 ed fa 8e d5 bc 00 7c fb fc 66 31 db 66 31 c9 |3......|..f1.f1.|
00000030 66 53 66 51 06 57 8e dd 8e c5 52 be 00 7c bf 00 |fSfQ.W....R..|..|
00000040 06 b9 00 01 f3 a5 ea 4b 06 00 00 52 b4 41 bb aa |.......K...R.A..|
00000050 55 31 c9 30 f6 f9 cd 13 72 16 81 fb 55 aa 75 10 |U1.0....r...U.u.|
00000060 83 e1 01 74 0b 66 c7 06 f3 06 b4 42 eb 15 eb 02 |...t.f.....B....|
00000070 31 c9 5a 51 b4 08 cd 13 5b 0f b6 c6 40 50 83 e1 |1.ZQ....[...@P..|
00000080 3f 51 f7 e1 53 52 50 bb 00 7c b9 04 00 66 a1 b0 |?Q..SRP..|...f..|
00000090 07 e8 44 00 0f 82 80 00 66 40 80 c7 02 e2 f2 66 |..D.....f@.....f|
000000a0 81 3e 40 7c fb c0 78 70 75 09 fa bc ec 7b ea 44 |.>@|..xpu....{.D|
000000b0 7c 00 00 e8 83 00 69 73 6f 6c 69 6e 75 78 2e 62 ||.....isolinux.b|
000000c0 69 6e 20 6d 69 73 73 69 6e 67 20 6f 72 20 63 6f |in missing or co|
000000d0 72 72 75 70 74 2e 0d 0a 66 60 66 31 d2 66 03 06 |rrupt...f`f1.f..|
000000e0 f8 7b 66 13 16 fc 7b 66 52 66 50 06 53 6a 01 6a |.{f...{fRfP.Sj.j|
000000f0 10 89 e6 66 f7 36 e8 7b c0 e4 06 88 e1 88 c5 92 |...f.6.{........|
00000100 f6 36 ee 7b 88 c6 08 e1 41 b8 01 02 8a 16 f2 7b |.6.{....A......{|
00000110 cd 13 8d 64 10 66 61 c3 e8 1e 00 4f 70 65 72 61 |...d.fa....Opera|
00000120 74 69 6e 67 20 73 79 73 74 65 6d 20 6c 6f 61 64 |ting system load|
00000130 20 65 72 72 6f 72 2e 0d 0a 5e ac b4 0e 8a 3e 62 | error...^....>b|
00000140 04 b3 07 cd 10 3c 0a 75 f1 cd 18 f4 eb fd 00 00 |.....<.u........|
00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000001b0 80 b6 05 00 00 00 00 00 12 c1 b1 38 00 00 80 00 |...........8....|
000001c0 01 00 00 ab e0 fc 00 00 00 00 80 bf 55 00 00 fe |............U...|
000001d0 ff ff ef fe ff ff a4 06 00 00 40 1f 00 00 00 ce |..........@.....|
000001e0 72 5d 83 22 d5 cd 00 c0 55 00 00 cc 98 00 00 00 |r]."....U.......|
000001f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 55 aa |..............U.|
00000200


=============================== StdErr Messages ================================

File descriptor 63 (pipe:[237540]) leaked on lvs invocation. Parent PID 37359: /bin/bash

Unmount sdc3 from /media/bwg/New Volume/ to avoid special characters (& or \ or space) incompatibilities

Suggested repair: ______________________________________________________________

The default repair of the Boot-Repair utility would reinstall the grub-efi-amd64-signed of
sda7,
using the following options: sda1/boot/efi,
Additional repair would be performed: unhide-bootmenu-10s win-legacy-basic-fix use-standard-efi-file

Final advice in case of suggested repair: ______________________________________


Please do not forget to make your UEFI firmware boot on the The OS now in use - Linux Mint 20.1 CurrentSession entry (sda1/efi/****/shim****.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\****\shim****.efi (**** will be updated in the final message)

I don't see any obvious problems. Your UUID for Manjaro: 0278b3bc-29f3-4e63-b2a2-ad71c46f67d9 shows in the Mint Grub. You might check the /boot/grub/grub.cfg file for the Manjaro entry to see if it has the same/correct UUID. I doubt that is the problem but no harm in checking.

If you look at the UEFI section of boot repair and the output of efibootmgr -v you see that the boot order shows 00003 (ubuntu) as first in boot order. I thought Mint changed that but many of the Ubuntu derivatives still use the ubuntu label in UEFI. This means Mint is set to boot first and that if you want to remove Manjaro, there is no need to mess with Grub. Simply boot the Mint install USB which should have GParted on it. You can use it to format sda8 (Manjaro partition) ext4 which should be the default on Mint. You can check this with the command: sudo parted -l (Lower case Letter L in the command). You can then use GParted to extend sda7 to sda8 as they 'appear' to be contiguous. You can verify this with the command: sudo fdisk -l. If you don't understand the output, post it here and someone will explain.

Before messing with partitions, make sure you have current backup. If you don't and something goes wrong, you lost and not likely to get any sympathy. Good luck.

1 members found this post helpful.

thank you very much for the good advice. I really do appreciate it.
Bruce

At mint grub menu press c for the grub command line
press enter, if it comes up with the manjaro grub menu and it boots, can add a grub menu entry in mint /etc/grub.d/40_custom that will show up in mints grub menu.

"windows and mint boot just fine from Mint's grub. However if the Manjaro wont boot from the Mint grub menu.
But if I restart and go to bios (or efi) menu I can choose Manjaro and the bios runs the Manjaro grub."

I didn't wade through all the posted info. My thought is that yes, you have a manjaro grub but it should be chain loaded from another loader. ???

I reduce potential for confusion caused by overlapping UEFI names among derivative distros by changing on first post-installation boot of such a distro the GRUB_DISTRIBUTOR= line in /etc/default/grub to be anything other than the distro's default. For this OP, because of boot-repair's efibootmgr output, I'd simply make the one for Mint GRUB_DISTRIBUTOR="mint" or GRUB_DISTRIBUTOR="linuxmint". After doing so, next installation of a new kernel or other update of grub would create a new entry in /boot/efi/EFI/ named mint or linuxmint.

As to the reason why the default Grub's boot menu won't launch Manjaro or Manjaro's Grub menu I suspect it may be a difference in Grub installed version between the Debian derivatives and Manjaro. A mixture of Grub versions can cause the different ones to fail to play nice together, such as what looks like is happening here.

I avoid most who's got control issues by only installing Grub on the first Linux installation on a PC, and keeping NVRAM free of others by whatever means necessary, including installation of no boot loader on others. If a switch to another is wanted at some point, adding Grub to that other is easy enough, followed by removing it from the previous one. My only currently booted UEFI PC, an AMD on an Asus, has a grand total of two entries in efibootmgr output, one for the control distro, "Boot0000* controldistro", and "Boot0002* UEFI OS". As further insurance against usurpation, I remove the ESP partition from the fstabs of the non-controlling distros.

The top portion of the Grub menu seen at boot on mine is generated by the custom.cfg I create from scratch and put in the grub* directory of the boot control distro. Here's an example:Custom.cfg is incorporated ahead of generated entries in grub.cfg via renaming /etc/grub.d/40_custom 06_custom, and/or 41_custom 07_custom. It uses symlinks to kernels so that it doesn't need to be altered each time a new kernel version gets installed somewhere among any of the installed systems.

1 members found this post helpful.

The major question here is does the Manjaro grub have an entry for Mint (it should) and can it boot Mint.

When multi-booting Linux distros the newest grub should always take control. This is the first rule. Mint is based on Ubuntu LTS which comes out every two years while Manjaro is a rolling distro. It is not surprising that Manjaro might have a newer version of grub that Mint can't boot.

Your problem might have been avoided simply by placing Manjaro at first priority in EFI. This can be done with a single efibootmgr command. Even if you preferred to run Mint the proper way to set it up was with the newer Manjaro grub in control.

If the Manjaro grub can boot Mint as well as Manjaro itself it should be first priority in the EFI variables.

Such a rule is for those who want others controlling their lives. Those who wish to be in control will choose one OS's Grub to be in control, and take steps to prevent all others from usurping control, and possibly making everything unbootable. Only one bootloader per Linux PC is required. All others can be omitted, saving time and headaches.

No, I would also disagree with that as it is simply default behavior and certainly does not apply in this case where the user is happy to format and dispose of the Manjaro partition. As to whether Manjaro has an entry for Mint, that would depend upon whether the OP ran grub-mkconfig from Manjaro after installing Mint. Given the circumstances, I doubt that.

However in this case the OP may not be interested in double booting Mint and Manjaro. For users actually interested in dual booting these two it would be the simplest advice.

Possibly true in this case however as said for someone actually interested in dual booting these two it would be trivial to run grub-mkconfig from Manjaro and then set Manjaro as first priority.

If you expect the OP and everyone else to follow your complex advice of removing all other bootloaders aren't you controlling their lives. Many others follow this simple rule and save themselves "time and headaches".

If the OP had simply done this they would not have this problem in the first place.