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Here is the story:

  1. Windows 10 was installed in BIOS/CSM Mode
  2. Converted the Disk to GPT (from MBR) - Success
  3. Unable to Boot in to Windows :/
  4. Manually Created the EFI & MSR partitions using diskpart - No luck
  5. Installed Lubuntu with Grub - Success
  6. Installed rEFInd - Success (shows only Lubuntu)
  7. Still unable to boot in to Windows

Current Situation

  1. Lubuntu - Mode: EFI || In /dev/sda3
  2. rEFInd - Mode: EFI || In ESP /dev/sda1
  3. Grub - Mode: EFI || In /dev/sda
  4. BIOS - Mode: CSM Disabled
  5. Secure Boot Configuration not available in BIOS

Grub Custom Configurations Tried:

Menu Entry #1 : Shows ERROR cannot load NTLDR (It's obvious about NTLDR being BIOS/CSM Module

set root='(hd0,gpt5)'
insmod ntfs
insmod part_gpt
search --no-floppy --fs-uuid --set 54AC831BAC82F6B0
ntldr /bootmgr

Menu Entry #2 :

set root='(hd0,5)'
search --no-floppy --fs-uuid --set 54AC831BAC82F6B0
drivemap -s (hd0) ${root}
chainloader +1

I believe it's a case of Hybrid Booting where in I've the

  1. Hardware (BIOS) setup in EFI
  2. EFI Boot manager (rEFInd) setup in EFI
  3. Grub2 setup in EFI mode
  4. Windows 10 setup in Legacy/MBR mode

Goal: I need to boot in to Windows/NTLD. Looking for help. Already spent 3 days figuring a solution.

ESP/EFI Partition Directory Structure for reference

Screen Shot of partition table - gparted

  • Legacy boot can not read a GPT disk. you could have easily installed ubuntu in EFI mode on an MBR disk if so desired. Your current fix for booting Windows. convert back to MBR and hope the Windows installation survived both conversions. – ravery Nov 24 '17 at 22:14
  • 1. Everything is in EFI. Except for the Windows installed in MBR. 2. Ubuntu is installed in EFI mode on /dev/sda3 3. There is no intent of converting the whole disk back to MBR. It will destroy the partition table. Did you read the whole thing? – Gagan Nov 24 '17 at 22:17
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    and? Window in legacy mode can not read a GPT disk it will never boot until the disk is changed to MBR. converting the disk to GPT was unnecessary and the source of your problem. – ravery Nov 24 '17 at 22:19
  • A MBR Windows installation cannot be converted to boot from GPT (and vice-versa, a GPT Windows installation cannot be converted to boot from MBR). – AlexP Nov 24 '17 at 23:01
  • @AlexP intel.in/content/www/in/en/support/articles/000024558/… Here's a link for conversion. – Gagan Nov 24 '17 at 23:36
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[Update - Fixed]

I got this done! I can dual boot Windows 10 and Lubuntu. Both are working in EFI mode. The Disk is in GPT. Here's what I did.

List of Tools:

  1. Yumi - UEFI version (Link)
  2. Lubuntu Live CD - Just in case
  3. Ubuntu Boot Repair Disk - Just in case (Link)
  4. (Windows PE) Gandalf's PE - (Link)

The next step was to get all these tools in 1 USB. I used Yumi to first install Lubuntu, then Boot Repair Disk and then finally Gandalf's PE.

I booted the system using Gandalf's PE. I followed the guidelines and materials from Rod's Book, very useful and insightful.

Mounting EFI partition - using diskpart

I'm going to briefly state the steps (14 onwards) from this Microsoft TechNet Wiki

  1. Select the Disk
  2. Assign a letter your EFI drive (let's say B:)
  3. Exit diskpart
  4. Change your directory to the EFI partition

cd /d B:\EFI\Microsoft\Boot bootrec /fixboot

Creating a BCDstore using bcdboot

We are still in the WinPE environment and since C: Drive is being used by the PE, we need to see where is the Windows which we need to restore installed. Let's say Z:, "/l" switch is used for providing the language and "/f" switch will be used for generating the BCD store for UEFI or BIOS or ALL.

bcdboot Z:\Windows /l en-us /s B: /f ALL

That's all I rebooted the system and rEFInd recognized the Windows EFI :) :) :) :) :) . It took a bit of time for Windows to boot up. But it's working absolutely fine.

Goal achieved : Converted Disks to GPT, Converted Windows BIOS to UEFI, Dual Booted Lubuntu and Windows 10 :)

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