Cannot Update to Windows 10 1903 on System with Unique Bootloader Setup

Oct 31, 2019
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Hi folks,

Got a problem with updating a machine to Windows 10 1903. It's kind of an unusual situation, though.

This particular machine has a cheapo RAID card in it along with two 2 TB hard drives configured in a RAID 0 array.

Because it is a 4 TB volume, it had to be configured as a GPT partition. However, this is an older machine that does not have UEFI; it is BIOS only. Which means that Windows 10 did not support booting from a GPT partition and there was no room to add a third hard drive with an MBR boot partition.

Following some instructions I found online (see below), I moved the Windows bootloader to a USB flash drive that has an MBR partition. This has worked flawlessly in allowing Windows 10 to boot properly and still be housed on a GPT partition even though this is a BIOS system.

Recently, however, I have been trying to do the update to version 1903, since the current version (1803) goes unsupported as of November 12th. Every time, whether through automatic updates or through the manual installer, the update appears to download and install. But then when it goes to reboot, there is no indication that it is actually doing any work, and when it reboots, it is still on 1803. The attempted update does not show in the update history, nor are there any errors in Event Viewer related to the update attempt. It's as if it just never happen.

Here are the instructions I referenced:
Booting Windows 7 / 10 from GPT Disk on BIOS (non-UEFI) systems | Windows OS Hub

I know that there was a known issue updating to 1903 on systems that have a USB flash drive or SD card attached, and that Microsoft had put a safeguard hold on updating those systems earlier this year. However, according to Microsoft, that issue was resolved as of July 11th and the safeguard hold was removed. So I am assuming that is not the issue in play here.

Does anyone have any idea what's going on? Could this be some problem due to the unique setup with the bootloader? Or do you think it is some other issue? How can I begin troubleshooting this?




Mar 4, 2016
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Hi Tom, Welcome to the Forum.

Have you considered using Microsoft's built in tool MBR2GPT to convert your legacy Bios to UEFI?
  • Press Windows key + X together, then select Shutdown or sign out, then while holding down the Shift key click on Restart

    Doing that will cause your computer to reboot to the Advanced Startup screen

  • On the Advanced Startup screen select Troubleshoot | Advanced options | Command prompt

  • Next validate your Hard disk using this command:

    mbr2gpt /validate

    Press Enter key to execute the command

  • If the previous command succeeds [ i.e. no errors pop up ], then start the conversion process using this command:

    mbr2gpt /convert

    Press Enter key to execute

    Using the /convert flag allows the System to add all the required UEFI boot files & GPT components. Then it will update the Boot Configuration Data.

  • Now restart computer, and go into your Bios and select UEFI to replace the current Legacy Bios startup

If you do that, I'm wondering whether you can then avoid your MBR USB drive altogether, and manage to upgrade to 1903.



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