PERP:  On one particular computer I installed ubuntu linux from a usb flash drive with the erase and install option. When done it prompts to remove the usb install media and when it tries to boot of of the hard drive it does not find a bootable disk

This usually means Ubuntu did install to the disk, but the firmware is not actually booting from its bootloader (GRUB) or is not seeing the disk as bootable at all.

To narrow it down, I need a bit more detail:

• What exact message do you see after POST? (“No bootable device”, “No operating system found”, error code, etc.).

• What computer/model and approximate age is it? (e.g., Lenovo Edge 71, HP desktop, laptop brand).

• In its firmware/BIOS setup, is the disk visible and listed in the boot order? Is it set to UEFI, Legacy/CSM, or a mix?

While you check that, here is the usual quick path to confirm and repair:

1. Boot from the same Ubuntu USB, choose “Try Ubuntu”.

2. In the live session, run lsblk and confirm your internal disk (likely /dev/sda or /dev/nvme0n1) has Ubuntu partitions (ext4, EFI, etc.).?

3. If the disk is present and looks fine, then:

   • If the machine is UEFI:

     • Ensure firmware is set to UEFI (not Legacy-only), Secure Boot preferably off, and that the Ubuntu entry (or an EFI file on the disk) is in the boot list.

     • If there is a “Select an UEFI file as trusted for executing” option under Security, point it to the \EFI\ubuntu\grubx64.efi on the internal drive, then put that new entry first in boot order.??

   • If it’s Legacy/BIOS:

     • Make sure boot mode is Legacy (or CSM) and the internal HDD/SSD is first in the boot order.?

     • From the live session, you can reinstall GRUB to the disk MBR:

       • sudo mount /dev/sdaX /mnt (replace sdaX with your Ubuntu root partition)

       • sudo grub-install --target=i386-pc /dev/sda

       • sudo chroot /mnt update-grub?

If instead the internal disk does not appear in lsblk or the BIOS/firmware, the problem is lower-level (cable/port, SATA mode like RAID/Optane/RST instead of AHCI, or the drive itself).

Reply with:

• Exact model of the computer.

• Exact boot error text.

• Whether BIOS shows the drive and in which boot mode (UEFI vs Legacy).

With that I can give you a very specific set of steps rather than general possibilities.

It messages "no bootable device". It is a Lenovo Edge 71. The disk is visible in BIOS. There is no setting in BIOS for UEFI or CSM.

On the Edge 71 this almost always means Ubuntu was installed in EFI mode, but the machine can only actually boot in Legacy/BIOS mode, so the disk has no Legacy GRUB in the MBR and the firmware declares “no bootable device”.

What’s going on on this Edge 71

• Edge 71 is effectively a Legacy?only box; there is no real UEFI/CSM toggle in BIOS despite some Lenovo docs implying UEFI.

• If the installer boots in UEFI mode, it creates an EFI System Partition and installs GRUB?EFI to it, leaving the disk MBR without boot code; a Legacy BIOS like yours then sees the disk but finds no bootable code and throws “no bootable device”.?

You already confirmed:

• Disk is visible in BIOS.

• There is no UEFI/CSM option.
  So the fix is to ensure Ubuntu (and GRUB) are installed in Legacy mode and GRUB is written to the disk’s MBR.

Fix path A: Reinstall Ubuntu in Legacy mode (cleanest)

1. Recreate the USB installer in pure BIOS/Legacy?bootable form:

   • Use Ventoy or Balena Etcher instead of Rufus; Rufus often defaults to UEFI?only images that confuse the Edge 71.?

2. Boot the Edge 71 and tap F12, then explicitly choose the USB entry that looks Legacy (no “UEFI:” prefix; usually just the USB name).

3. In the installer, again choose Erase disk and install Ubuntu (single?OS).

4. Let it finish, remove USB when prompted, and it should now boot directly from the HDD because GRUB has been installed to the MBR in Legacy mode.

This is usually the fastest way if you don’t care about keeping the current install.

Fix path B: Convert current install from EFI to Legacy (no reinstall)

If you want to salvage the existing install:

1. Boot from the Ubuntu USB, choose Try Ubuntu.

2. In the live session, identify the root partition:

   • lsblk → find your disk (likely /dev/sda) and the main ext4 partition (for example /dev/sda2).?

3. Mount it and chroot:

   • sudo mount /dev/sda2 /mnt (replace with your root).

   • If you have a separate /boot or others, mount them under /mnt too.

   • for i in /dev /dev/pts /proc /sys; do sudo mount --bind $i /mnt$i; done

   • sudo chroot /mnt

4. Install Legacy GRUB into the MBR:

   • grub-install --target=i386-pc /dev/sda

   • update-grub

5. Exit chroot, unmount, reboot, remove USB.

   • The BIOS should now see the disk as bootable and GRUB should load.

This is effectively what Boot?Repair did for the person in the UbuntuForums thread with this exact Edge 71 symptom; converting the install to Legacy mode fixed “This is not a bootable disk”.?

One quick check before spending time

Before doing either path, also rule out the silly case where GRUB got written to the USB:

• Boot again with the USB inserted, see if you get a GRUB menu and can boot the installed system from there.?

• If it only boots when the USB is present, then GRUB was likely installed on the USB and not /dev/sda, and reinstalling GRUB to /dev/sda as in path B is the right move.?

If you tell me:

• How you created the USB (Rufus options, etc.).

• Output of lsblk from a live session.

I can give you an exact set of commands tailored to your current partition layout (e.g., whether you have a useless EFI System Partition to ignore or reuse).

Please update for the following update response: It messages error 1962 no operating system found It is a Lenovo Edge 71. The disk is visible in BIOS. There is no setting in BIOS for UEFI or CSM.

Error 1962 on the Lenovo ThinkCentre Edge 71 after an Ubuntu "erase and install" means the installer created an EFI System Partition but no GRUB code in the disk's MBR, and since this BIOS is Legacy-only (no UEFI/CSM toggle), it can't find boot code and throws the error even though the disk is visible.

Why this happens on Edge 71

The Edge 71 BIOS (even latest 9QKT39A from 2012) is effectively Legacy/BIOS-only despite Lenovo calling it "UEFI"—it lacks proper EFI boot support, so Ubuntu installers defaulting to EFI mode leave the MBR empty and unbootable.?

Quickest fix: Reinstall in Legacy mode

1. Recreate USB installer with Ventoy or Etcher (avoid Rufus UEFI defaults).

2. Power on, tap F12 at Lenovo logo, select the Legacy USB entry (no "UEFI:" prefix).

3. Install with Erase disk and install Ubuntu.

4. Remove USB when prompted—it now boots via Legacy GRUB in the MBR.

Salvage current install: Install Legacy GRUB manually

Boot the Ubuntu USB in Legacy mode (F12), choose Try Ubuntu:

sudo apt update && sudo apt install boot-repair boot-repair

• Choose Recommended repair. It detects the EFI issue, converts to Legacy GRUB on MBR (/dev/sda), and fixes.

Or manually (if no network):

lsblk # note root partition, e.g. /dev/sda2 sudo mount /dev/sda2 /mnt sudo mount --bind /dev /mnt/dev sudo mount --bind /proc /mnt/proc sudo mount --bind /sys /mnt/sys sudo chroot /mnt grub-install --target=i386-pc /dev/sda update-grub exit sudo reboot # remove USB

This writes GRUB to the MBR exactly as Boot-Repair does.?

Verify success

After fix, in running Ubuntu: ls /sys/firmware/efi should fail (confirms Legacy mode).?

If Boot-Repair paste shows EFI remnants post-fix, purge them with GParted (delete fat32 ESP, resize root partition) but usually unnecessary. This resolved the identical "installs but disk is not bootable" on Edge 71.

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