14.04 - Ubuntu EFI boot problem - Dell Inspiron 13-7359

After a clean install (pre-installed Win 10 removed) of Ubuntu 14.04.4 on Dell Inspiron 13-7359 I am not able to boot the OS in "Secure mode".

What was done:

1. First installed standalone Ubuntu 15.10 - installation OK, but in BIOS there was no visible device (for EFI mode), which I could boot from. After several re-installations ("Auto" Erase and install, Manual partitioning, ...) there was no progress.


2. Installed standalone Ubuntu 14.04.4. Installation OK, didn't boot to OS. BIOS found a disk to boot from, but this message appeared: "Operating system loader has no signature.". Tried Boot-repair from live disk - no progress. Pastebin report.

Current situation - Ubuntu boots in "Non-secure" Legacy mode. Everything works fine.

I'm curious what I did wrong, as there is always solution - I didn't find it, even there are some Q&A to similar problems Nothing helped me out of this.

Update:

After reading answers, identified that the problem probably lies in installation USB media, tried following solutions (8 GB USB flash formatted to FAT32 FS)

• Disks (gnome-disk-utility) application in Ubuntu 15.10
  
  
  
  
  • created bootable Ubuntu 14.04.4 USB flash
  
  
  • media was not visible in ntb BIOS in UEFI & SecureBoot configuration
  
  



• dd in terminal (Ubuntu 15.10)
  
  
  
  
  • created bootable Ubuntu 14.04.4 USB flash
  
  
  • not visible in ntb BIOS in UEFI & SecureBoot configuration
  
  


• Rufus (in Win7)
  
  
  
  
  • Bootable USB flash with GPT for UEFI (Rufus option)
  
  
  
  • created Ubuntu 14.04.4 live USB flash
  
  
  • visible in ntb BIOS
  
  
  • din't boot in UEFI & SecureBoot configuration
    
    
    
    
    • Error Message: "Operating System Loader signature not found in SecureBoot database"
    
    
  
  
  • But USB booted successfully with UEFI On & SecureBoot Off configuration (path to boot file : /EFI/boot/grubx64.EFI)
  
  
  • Try to install in automatic mode "Erase and reinstall" offered to create only main ext4 and swap paritions
  
  
  • In "Something else" option, I was able to managed creating an ext4 main partition, a 8GB swap and a 601 MB EFI partition (previously reserved 201 MB was not enough for the installer)
  
  
  
  • Installation OK
  
  
  • After reboot SecureBoot enabled and booted in UEFI & SecureBoot configuration
  
  
  • Also there is a folder /sys/firmware/efi now (which should indicate that there was no fallback to compatibility mode)
  
  
  • => Problem Resolved
  
  

You've installed Ubuntu in BIOS/CSM/legacy mode. I recommend you disable the Compatibility Support Module (CSM; aka "legacy boot support" or similar terms) in your firmware. Doing this will render some boot media unbootable. If you run into this problem, the solution is to fix the boot media. If you want to boot in EFI/UEFI mode, enabling the CSM is the worst thing you can do. For more on this subject, see my Web page about it.

Note that in EFI mode you do not boot from a "device"; you boot from a boot loader file, which is stored on the FAT EFI System Partition (ESP) and referenced in an NVRAM boot manager entry. There is one sort-of kind-of exception to this rule: EFI supports a "fallback" boot filename, which is EFI/BOOT/bootx64.efi for 64-bit (x86-64) systems. If no other boot entry is valid, or sometimes if there's an explicit entry for this loader, the system will boot it. This feature enables booting from OS installation media. It's also sometimes used to boot systems with badly broken EFIs that ignore or forget their NVRAM entries. This fallback entry may appear in the computer's built-in boot manager much like a traditional BIOS boot-from-device entry, but it's not quite the same thing.