Windows 10: No bootable device found after converting HDD to MBR.

A few days ago I installed Samsung NVMe SSD and did a clean windows installation on SSD. Unfortunately, my HP CC Pavilion laptop didn't show SSD in UEFI OS Boot Manager, and hence, I enable legacy mode and kept SSD on top. I wiped my HDD partition where OS was installed. Everything was working smooth, until I converted my HDD to MBR in order extend storage to another HDD partition. I did this by going into CMD in recovery mode. Now, my HDD is converted to MBR but on starting laptop it prompts "No bootable device found...". I checked legacy mode and it's same as before SSD selected as 1st boot

:)

 

clone MBR HD to bootable GPT partition?

Hi,

1. You cannot convert mbr to gpt without data loss. otherwise, you can follow directions here:

FROM WINDOWS RECOVERY CONSOLE:

To change a master boot record disk into a GUID partition table disk using a command line

• 
  Back up or move the data on the basic master boot record (MBR) disk you want to convert into a GUID partition table (GPT) disk.
  
• 
  Open an elevated command prompt (right-click Command Prompt, and then click Run as Administrator) and type diskpart. If the disk does not contain any partitions or volumes, skip to step 6.
  
• 
  At the DISKPART prompt, type list disk. Make note of the disk number you want to convert.
  
• 
  At the DISKPART prompt, type select disk <disknumber>.
  
• 
  At the DISKPART prompt, type clean.
  

2. I'd suggest converting your vista drive to a virtual machine, load that up on your windows 10 system and use a program like virtualbox to run it.

 

Convert only one partition on the disk from MBR to GPT

Follow the steps listed here on using GPTgen. He also lists how to create and restore backups.

Converting MBR to GPT without deleting your partitions

 

Convert only one partition on the disk from MBR to GPT

Step 2
Convert MBR to GPT without data loss