[RESOLVED] GRUB can't find any OS installations, after partition resizing

[jasoncollege24]

If this is in the wrong forum, please feel free to move it.

System specs are at the bottom of this post, in case they're needed.

Here's the situation:

I dual boot between Windows 11, and Kubuntu 22.04, but I'm also looking at testing different Distros, that require a larger EFI partition than what Windows sets up.

1. Using MiniTool Partition Wizard for Windows, I resized my Windows C partition, shrinking it by 512MB, and moving it to the end of the newly created free space
2. Used the same app to remove the unnecessary 16MB partition that Windows creates, then resized the EFI partition to fill the newly created 512MB of free space.
3. All other partitions (including the Linux root partition) have remain untouched.

GRUB itself loads perfectly fine, and the expected list of boot items is shown. Problem is that selecting either Windows or Kubuntu from that list results in a message that the boot item can't be found, and then returns to the GRUB menu.

Windows 11 also boots fine, as long as I choose it's boot loader directly from the UEFI/BIOS, or the boot loader screen (F11 during POST).

There are still preparations I need to make, and files I need to grab before I start distro testing, so I need to get into that install. Any help repairing GRUB would be greatly appreciated. Thanks in advance!

System: Custom Desktop PC
Motherboard: ROG STRIX Z390-F Gaming (LGA1151)
CPU: Intel Core i9-9900K @ 3.70GHz (8 cores, 16 threads)
RAM: 32GB Dual Channel G-Skill Trident Z RGB (F4-3200C16-16GTZR x2)
Graphics: NVidia GeForce RTX 2080 Super (8GB)
Sound: RealTech HD Audio
Display 1 (Secondary): HP 1080p Monitor
Display 2 (Primary): Vizio 43" 4k UHD Home Theater Display
Display 3 (Third): Samsung 1080p HDTV (Used in place of Display 2, if needed)
Network type: Wi-Fi/Ethernet (Interchangeable, but almost exclusively Ethernet with gigabit speeds)
Storage Space: LOTS (All operating systems run from SSDs)
Control type: Keyboard, Mouse

[TinyTim]

512 MB is tiny. I'm don't have a lot of experience, but I think you need to update your GRUB.

[jasoncollege24]

the EFI partition was created by Windows. The original size was 100MB. I added 512MB to that.
I'm not sure how to update this change in GRUB

[claydoh]

Since you moved stuff around, and changed sizes of things, the UUIDs for the partitions, or other identifiers will also have changed.
You probably can repair Kubuntu's grub by installing/using boot-repair from a *buntu live USB.
This iirc can reinstall grub, which should probe for Linux and Windows installs
But having moved Windows, its bootloader is definitely going to be borked, I think. Grub just hands booting over to Windows' boot loader,when selected iirc.
Windows probably can be repaired using whatever method is needed there - probably a repair from a Windows installer USB.

[jasoncollege24]

Windows loads fine, if I choose it's boot loader directly from the UEFI, so Windows itself wasn't messed up.

I ran boot repair, and it reinstalled GRUB with multiple errors. Windows can now be booted from grub, but when in boot repair, I checked the pastebin and it said i needed to reinstall grub manually. attempting to boot into Linux, gives a message that the linux root partition needs a manual fsck. it also suggested i contact their email address with this info

[jasoncollege24]

This was resolved by running boot-repair from a Live USB (as suggested above), and then running

fsck -yf

on the root partition from the initramfs prompt. Marking this as resolved. Thanks for the help!

[oshunluvr]

Glad you found the solution and thanks for reporting back.

[oshunluvr]

512 MB is tiny. I'm don't have a lot of experience, but I think you need to update your GRUB.

Common belief is 512MB is an excessive amount for EFI unless you're installing more than 8 OS's or some that store more in that directory than standard , as the OP suggests.

My Windows+Kubuntu GRUB-EFI laptop has a 256MB EFI partition with 221.5MB free space - only 34.5MB used. IIRC early Windows 10 defaulted to 256MB or 512MB but later versions appear to default to 100MB because that's plenty for most users.

Updating GRUB - assuming "sudo update-grub" was the intended suggestion - would not have any effect on usable EFI partition space. It would only update the EFI menus.


Also worth noting that the amount of drive space we're talking about makes the EFI size almost irrelevant. 1/4, 1/2 or even 1 GB isn't much real drive estate these days.

[jasoncollege24]

I was attempting to test a Linux distro that wanted at least 350MB free in the EFI partition. I chose to increase the 100MB EFI partition that Windows created by 512MB as a convenient number. I know the total beyond what is needed is just wasted space, but I have enough SSD space to not be worried about taking that much from Windows.

Windows booted perfectly fine, when it's bootloader was chosen directly from the UEFI Boot menu. Grub needed to be reinstalled, and a manual fsck needed to be run on the Linux root partition to resolve the issue.

Thanks for all the help!

[Qqmike]

Re the EFI partition, the ESP:

Size depends on HOW you will add more OSs.
Basically, if you want to store the kernel, for example, and/or any other boot info in the OS sub-directory of the ESP, THEN you need enough space to do so.

[TinyTim]

Common belief is 512MB is an excessive amount for EFI unless you're installing more than 8 OS's or some that store more in that directory than standard , as the OP suggests.

My Windows+Kubuntu GRUB-EFI laptop has a 256MB EFI partition with 221.5MB free space - only 34.5MB used. IIRC early Windows 10 defaulted to 256MB or 512MB but later versions appear to default to 100MB because that's plenty for most users.

Updating GRUB - assuming "sudo update-grub" was the intended suggestion - would not have any effect on usable EFI partition space. It would only update the EFI menus.


Also worth noting that the amount of drive space we're talking about makes the EFI size almost irrelevant. 1/4, 1/2 or even 1 GB isn't much real drive estate these days.

Thanks for the information. There was more to it than what I was understanding.