Automatically booting from SSD not working as expected?

Question

I bought a Lenovo ThinkCentre machine, used.

I've installed Ubuntu from an USB flash drive. When I start the machine, it says, no bootable device found. I went into BIOS and set the primary boot device to my SSD.

When I installed Ubuntu, I set /dev/sdb as boot device, since, this is the SSD.

But as I see, now I have only sda, because I've plugged out the USB flash drive.

If I am just press F12 at startup, and select the SSD, then everything is okay, and boot normally.

What should I do to automatically start my installed Linux?

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Additional info:

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sdb5 during installation
UUID=21711b13-9c18-44d6-8ff7-315df9bb8ae1 /               ext4    
errors=remount-ro 0       1
# /boot/efi was on /dev/sdb1 during installation
UUID=3F43-CCA2  /boot/efi       vfat    umask=0077      0       1
/swapfile                                 none            swap    sw              0       0

This is in fstab but how can I edit it for GRUB?

The GRUB loader does not start, when I just hit F12, it immediately loads the Linux.

Anyway, the error is:

“Error 1962: No operating system found...”

Answer 1

Are you booting using UEFI? Probably, you need to create a correct boot entry in the firmware. I wonder why it wasn't created. Maybe, a buggy UEFI BIOS?

To see and check boot entries from Linux, run efibootmgr (or efibootmgr -v to see more verbose output). I think it worth adding it into the question (by editing it). Also it's worth checking boot entries using BIOS setup, if it has such a feature.

To let the system automatically create or update a boot entry, run update-grub. You can also do this manually, feel free to read this manual page for details about it (and don't worry about Gentoo: that page is actually about this software package, efibootmgr, which is the same in all distros).