This is my situation:

I had Acer E15 with win10 on an SSD and secondary empty HDD. I replaced the HDD with another SSD and re-installed win10 on the new SSD. Then I tried installing Ubuntu 18.04 on the original SSD to have dual boot. I followed this: Dual Boot Windows 10 and Linux Ubuntu on Separate Hard Drives

While doing the partitions I had an existing EFI partition on the original SSD which had label like "windows boot loader". I deleted that one thinking linux EFI would be good enough for the Grub menu to show and identifying both OS. It didn't work out and got the "no bootable device" message. I did re-install linux again but same problem. I did disable safe boot through installs. I used this to fix the no bootable device thing: https://itsfoss.com/no-bootable-device-found-ubuntu/ but still no grub menu. I updated grub as well and still don't have the dual boot. How can I do that? Is it possible at all at this point to have dual boot of the existing win10 and ubuntu?

  • Do you have an EFI partition now? When you say you were "doing the partitions" it sounds like you used manual partitioning. You do need to ensure an EFI partition exists and mount it at /boot/efi. If you removed the EFI partition and you don't have one on your Win10 SSD, you may have hosed Windows. – user595510 Jun 15 '18 at 14:10
  • Thanks, that sounds like it! As I said there was one EFI partition for WIN10 but instead of using it to add boot loader of ubuntu I deleted and created a new EFI partition. As mentioned I already have the ubuntu running. Second problem is win10 usb doesn't load at all and I keep getting into ubuntu. USB has highest priority in BIOS but for some reason it's not being used. How can I fix that? – embi Jun 19 '18 at 18:31
  • By the way, why the guide I used doesn't work? Should I really must have kept the Win10 EFI partition? I don't even know if I'm using right terminology by saying win10 efi and ubuntu efi... – embi Jun 19 '18 at 18:38
  • You can't destroy the Windows EFI partition. You should only have one EFI partition in general. A single EFI partition will properly handle both Ubuntu and Windows. – user595510 Jun 21 '18 at 13:35
  • As for the USB stick, does it have an EFI folder on it? Is it marked as bootable/active? – user595510 Jun 21 '18 at 13:36

Although by EFI spec. the only requirement for the EFI partition is that it be formatted FAT, specific hardware may have added additional requirements for windows, such as which partition it is, or that there must be a recovery partition, etc.

Assuming both SSDs are internal, This is what I'd do:

Be sure, the hardware is set to EFI mode only, and secure boot is off.

First, Install Windows to the first SSD, and be sure it boots. Then turn off Fast start up in windows.

Next, Install Ubuntu. When partitioning select "Something Else" to manually partition. Be sure that Ubuntu has selected the EFI partition on the first drive (the one Windows made), and that it has not selected to make a new one on the second drive. Create your Ubuntu partitions on your second drive. and install it.

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  • Thanks! Is there anyway I can revive the existing win10? How can I know it's doable? I guess I have ruined the windows boot system (not sure) I'm willing to re-install the Ubuntu but not the win10. I'd probably forgo having windows altogether if I can't get the current windows going. – embi Jun 14 '18 at 19:43
  • swap the drives so Windows is on the first SSD – ravery Jun 14 '18 at 19:50
  • Problem is bigger than that as I think I don't think I have the boot loader for windows anymore.... Plus the SSDs cannot be switched as one is NVMe and other SATA :/ – embi Jun 19 '18 at 18:36
  • which is the NVMe? possibly that is the issue – ravery Jun 19 '18 at 19:10
  • original SSD which had win10. Now win10 is sitting on SATA SSD and ubuntu went on NVMe SSD. – embi Jun 19 '18 at 21:54

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