I have a Dell Inspiron 3558. It came with Windows 10 installed.

I was trying to replace Windows 10 with Ubuntu. The live USB boots in UEFI.

I created a new partition table:

gparted - all partitions

After installation I am unable to boot ubuntu in UEFI.




No Os found by the system

Tried Boot repair. Here's the Boot Summary:


  • The boot info shows you installed Ubuntu in BIOS mode so you should be able to boot it with legacy on. – user589808 Sep 4 '16 at 14:09

Your setup is a bit confused. It might be made to work, but is a bit sub-optimal, at best. Specifically:

  • You have a BIOS/CSM/legacy-mode GRUB installation. This creates any number of potential problems; see this page of mine for details.
  • There's no evidence of an EFI/UEFI-mode GRUB installation on your computer. Thus, the only way you'll boot the computer in its current state is in BIOS mode. To boot in EFI mode, you must install an EFI boot loader. Boot Repair should be able to do this.
  • Your partitions aren't optimally sized....
    • Your ESP (/dev/sda1) is 237 MiB. Although this is big enough to hold the necessary files, some EFIs have buggy FAT drivers that cause them to behave strangely with FAT32 partitions under 512 MiB; and some EFIs have problems with FAT16. Thus, I recommend making the ESP 550 MiB in size. (That's big enough to work around MB-vs-MiB confusion and to ensure that mkdosfs creates a FAT32 filesystem by default.) Note also that an ESP is unnecessary if you boot in BIOS mode.
    • Your BIOS Boot Partition (/dev/sda5) is grossly oversized. It's 200 MiB in size, but 1 MiB is normally adequate. (I've seen some reports of cases where it must be 2 MiB, but these seem to be quite rare.) This isn't really causing any problems except for the wasted disk space. Note also that this partition is unnecessary if you boot in EFI mode; it's used only by the BIOS-mode version of GRUB.
    • You've got 14.66 GiB of unallocated disk space. If you intend to use that for something, then fine; but if it's an oversight, you might want to correct it before going any further.
  • Your Boot Repair output indicates that the tool booted in EFI mode, which is usually best for an EFI-based computer; but as noted earlier, you have only a BIOS-mode GRUB, which indicates you installed Ubuntu in BIOS mode. If you want to boot with the current boot loader, you must re-enable BIOS/CSM/legacy support in your firmware, and perhaps tweak your boot order settings; but if you want to boot in EFI/UEFI mode, you should use Boot Repair in its current EFI-mode boot or some other tool to install an EFI-mode boot loader -- or start over from scratch (see below).
  • Your root (/) partition is /dev/sda2, which is 325.96 GiB in size. Given that you've got a separate /home partition, chances are your root (/) partition is oversized. Normally, 30 GiB or so is plenty for a root (/) partition if you have a separate /home. There are exceptions to this rule, though, such as if you'll be running a server that stores lots of stuff in /var (or anywhere other than /home). The system on which I'm typing this has a 45 GiB root (/) partition, of which 30 GiB is used. I have a lot of kernel source code in /usr/src, though, so I have more in / than most do. (I've also got a separate /home.) If you're experienced enough to know that you really need an over-300 GiB /, then fine; but if not, you may want to cut it back significantly and put the space in /home.

Given that this is a new installation, you might want to start over again. I recommend disabling BIOS/CSM/legacy support and double-checking that you've booted the installer in EFI mode. (Do this by launching in "try before installing" mode and opening a Terminal window. Use that to look for a directory called /sys/firmware/efi. If it's present, you've booted in EFI mode; if it's absent, you've booted in BIOS mode. To install, click the installer icon or type ubiquity in the Terminal.) You can then delete the current partitions, create a more optimized set of partitions (with different sizes, as noted above, and omitting the BIOS Boot Partition), and re-install.

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