Solved Uefi: some installation media not found in BIOS

[Tout]

Hi,

I'm trying to install Linux Mint on a desktop. I've downloaded, verified and copied the image onto a usb drive.

It is not showing up as a UEFI device in the selection of boot devices.

I can make the disk appear when I turn on CSM (compatibility mode), it will see the MBR partition and go (but it will install the system without UEFI, that is not desired)

The image and thus the disk contain a MBR and GPT table. It's hybrid. There is an EFI partition on the disk.

The same happens for the Debian images.

The Ubuntu images are recognized fine. They show up as UEFI devices.

So far I tried:

Creating the disk with Etcher
Creating the disk with dd

Removing the MBR with wipefs (the dos br)

Several bios configs involving secure boot methods (standard/custom/windows). Turning it on and of, wiping keys, etc.

Doesn't help.

Oh the motherboard is an ASUS X870E Creator Wifi (fun fact: the bios of this motherboard takes a minute or so to boot after a change in settings, you can imagine my workflow )

EDIT: It seems related to that motherboard, when I go into the BIOS of my older desktop, it sees the UEFI Mint image. That is an ASUS B350M-A btw.

Can you point me in a direction?

Kind regards

 

[Brickwizard]

Welcome to the forums,
so lets start with

Tutorial Thread 'Basic checks if Linux fails to install'

Nov 9, 2025

Why Linux fails to load/install direct to HDD, common reasons

1] Corrupt download [check SHA sum]
2] bad burn to installation medium [try again] [if you used Rufus then try Balena Etcher or Ventoy]
2A] if optical drive burn at slow speed [no more than x3]
3] Wind 8.2 and higher quick start/fast boot or secure boot not disabled [after disabling do a full power re-boot not a restart]
3A ] check that boot from USB/Optical drive is enabled in your BIOS?UEFI
4] defective pen-drive/DVD
5] hardware fault,
5A] If old style HDD run integrity check
5B]if SATA SSD check for hidden...

• Brickwizard
• Replies: 2
• Forum: Getting Started

• 

 

[deb_user]

It seems that most distros provide hybrid .iso files, for compatibility reasons. They will install in UEFI mode.

 

[Tout]

Welcome to the forums,
so lets start with

Tutorial Thread 'Basic checks if Linux fails to install'

Nov 9, 2025

Why Linux fails to load/install direct to HDD, common reasons

1] Corrupt download [check SHA sum]
2] bad burn to installation medium [try again] [if you used Rufus then try Balena Etcher or Ventoy]
2A] if optical drive burn at slow speed [no more than x3]
3] Wind 8.2 and higher quick start/fast boot or secure boot not disabled [after disabling do a full power re-boot not a restart]
3A ] check that boot from USB/Optical drive is enabled in your BIOS?UEFI
4] defective pen-drive/DVD
5] hardware fault,
5A] If old style HDD run integrity check
5B]if SATA SSD check for hidden...

• Brickwizard
• Replies: 2
• Forum: Getting Started

• 

Thanks!

I used 3 different drives (2 different NVME's in USB housing, one SD Card in usb adapter). I did try Etcher as well. Ubuntu installs fine from at least 2 of those media. Also Mint does install from the media if I use the MBR CSM config.

There is no booting involved yet, cause I cannot select the UEFI device as a boot device.

I guess that passes all applicable points you mentioned.

 

[Tout]

It seems that most distros provide hybrid .iso files, for compatibility reasons. They will install in UEFI mode.

Yes, that's the thing that puzzles me, I used all hybrid images. I checked as well looking at the partitions and GPT. But Mint and Debian are not recognized, Ubuntu is.

 

[Tout]

It seems related to that motherboard, when I go into the BIOS of my older desktop, it sees the UEFI Mint image. That is an ASUS B350M-A btw.

I also put this as an edit in the opening post.

 

[CaffeineAddict]

It seems related to that motherboard, when I go into the BIOS of my older desktop, it sees the UEFI Mint image.

Same USB with Mint or Debian shows up as UEFI on one computer but does not show up on ASUS X870E?

It would help if you post pictures of ALL UEFI/BIOS settings you have from ASUS X870E, you can use your phone to take the pics.

 

[Tout]

Same USB with Mint or Debian shows up as UEFI on one computer but does not show up on ASUS X870E?

It would help if you post pictures of ALL UEFI/BIOS settings you have from ASUS X870E, you can use your phone to take the pics.

Yes same USB drive. And yes on one computer shows up, on other does not.

Just to check I removed the drive from the usb housing and put it as an internal NVME. Same story, does not show UEFI. Does see the NVME drive in the NVME settings. Got the drive out again and will make some pictures of BIOS later.

 

[Trml]

Creating the disk with Etcher

If I understand the following article, they basically force UEFI by creating the usb partitions manually and copying the Mint ISO file onto the empty filesystem: https://www.thelasttech.com/post/enabling-uefi-boot-for-linux-mint-21-3-a-simple-guide

This way you can probably choose the USB as boot device in UEFI and select the ISO to boot.

It must be a general Mint problem. Another way I would have suggested is simply start the Mint live, create the partitions yourself and appoint them during the install (i.e. ESP, /boot, /, etc). I don't know the Mint installer, but Debian's (used to) allows that.

 

[Tout]

If I understand the following article, they basically force UEFI by creating the usb partitions manually and copying the Mint ISO file onto the empty filesystem: https://www.thelasttech.com/post/enabling-uefi-boot-for-linux-mint-21-3-a-simple-guide

This way you can probably choose the USB as boot device in UEFI and select the ISO to boot.

It must be a general Mint problem. Another way I would have suggested is simply start the Mint live, create the partitions yourself and appoint them during the install (i.e. ESP, /boot, /, etc). I don't know the Mint installer, but Debian's (used to) allows that.

The link you sent seems the regular way.

But the idea of manually creating the partitions and thus avoiding the hybrid way seems logical. So partitioning with only GPT, have the correct partitions for efi boot and copy the rest in an ext4 partition, copying it from a mounted iso. Worth a try.

 

[Tout]

The original partition scheme looks funny btw, the partitions overlap:

Disk /dev/sdb: 1.82 TiB, 2000398934016 bytes, 3907029168 sectors
Disk model: RTL9210B-CG     
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 33553920 bytes
Disklabel type: dos
Disk identifier: 0xd94bd83b

Device     Boot Start     End Sectors  Size Id Type
/dev/sdb1  *       64 5967263 5967200  2.8G  0 Empty
/dev/sdb2        8452   18691   10240    5M ef EFI (FAT-12/16/32)

 

[Trml]

have the correct partitions for efi boot and copy the rest in an ext4 partition

Skip the ext4 on the USB, EFI can't deal with it. Copy the ISO onto the EFI esp boot partition with GPT scheme, efi shell can be used to select the ISO is the idea to test.

 

[Tout]

Skip the ext4 on the USB, EFI can't deal with it. Copy the ISO onto the EFI esp boot partition with GPT scheme, efi shell can be used to select the ISO is the idea to test.

Yes that sound logical.

In the mean while I had a look at the Ubuntu install disk, partition wise:

Disk model: RTL9210B-CG    
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 33553920 bytes
Disklabel type: gpt
Disk identifier: B5416491-A6D3-42B2-A3F6-260427BCF601

Device        Start      End  Sectors  Size Type
/dev/sdb1        64 12383487 12383424  5.9G Microsoft basic data
/dev/sdb2  12383488 12393647    10160    5M EFI System
/dev/sdb3  12393648 12394247      600  300K Microsoft basic data

Disklabel type is gpt here, on the Mint one it is dos.


I decided to delete the sdb1 and sdb3 from the disk, and only leave the ubuntu EFI partition in place. And yes that gets detected in the BIOS

So now try to get Mint onto that disk like you said.

 

[Trml]

So now try to get Mint onto that disk like you said.

Let us know how it goes. If the UEFI menus don't let you select the ISO, we have to see.

Meanwhile I had a quick look at the Mint installer documentation. In step 5 you can choose the "something else" installation type. This will bring you to the disk partitioning, where you can set up your desired GPT layout and create the necessary partitions for Mint, or map existing ones. That should actually be the regular way, and should mean you can turn off the CSM mode again after installation. Again, just theory from my side. Maybe a user of Mint can confirm it.

 

[bob466]

Hi,

I'm trying to install Linux Mint on a desktop. I've downloaded, verified and copied the image onto a usb drive.

It is not showing up as a UEFI device in the selection of boot devices.

You said...you copied the ISO onto a Flash Drive. ?

If that's what you did...it won't show in the Boot Menu.

 

[deb_user]

It will if the drive is formatted for Ventoy. With a Ventoy drive you just do a normal copy of as many .iso files as desired to it, and it boots whichever you want. For a normal drive, however, something like dd or one of the Windows utilities is needed.

 

[Trml]

If that's what you did...it won't show in the Boot Menu.

Yeah, it won't show the boot menu like that usually. I came up with the thought while trying to make sense of the article I linked in #9. You have to rely on options of the UEFI shell to select it. When you use a virtual machine with UEFI to install an ISO, it basically does the same.

Ventoy as suggested by @deb_user boots on its own and presents the ISO it finds. May be an option indeed generally, but using it won't convince the Mint installer to default to GPT.

Still, I think this should be possible to do with the regular Mint installer. If you custom create a GPT partitioning, it should use that and install everything as usual. That's a very regular use-case. edit: If you have to enable CSM for the ISO to boot, that's a problem with the ISO image and does/should not mean you need to keep CSM on after the installation finished.

 

[Tout]

Let us know how it goes. If the UEFI menus don't let you select the ISO, we have to see.

Meanwhile I had a quick look at the Mint installer documentation. In step 5 you can choose the "something else" installation type. This will bring you to the disk partitioning, where you can set up your desired GPT layout and create the necessary partitions for Mint, or map existing ones. That should actually be the regular way, and should mean you can turn off the CSM mode again after installation. Again, just theory from my side. Maybe a user of Mint can confirm it.

So I tried this, creating a efi partion and a partition for /

Grub install onto that disk

Installation goes fine
Mint starts with bios in CSM mode

Restart and switched off CSM mode
Mint boots

And you are a hero

So we found a way when your BIOS does not recognize a hybrid UEFI situation, to install the UEFI compatible installation from CSM mode.

Thank you all

 

[Tout]

Yes same USB drive. And yes on one computer shows up, on other does not.

Just to check I removed the drive from the usb housing and put it as an internal NVME. Same story, does not show UEFI. Does see the NVME drive in the NVME settings. Got the drive out again and will make some pictures of BIOS later.

So I ended up with a work around that works for me. I did not feel comfortable sharing pictures, cause of the glossy monitor reflecting my whole living room and my sweet face But thanks for offering your help.