Updating to version 1903, operating system is running MBR instead of GPT
Updating to version 1903, operating system is running MBR instead of GPT
Hi, I encountered a similar situation when trying to upgrade to version 1903. The error stated "Windows cannot be installed because this PC has an unsupported disk layout for UEFI firmware." It appears the problem stems from using MBR instead of GPT on my disks. A few years ago, I installed a new NVMe drive and overlooked unplugging previous drives—including the old boot drive—which I had backed up and formatted before. This mistake caused persistent update failures right after the first attempt. I attempted various fixes but eventually had to reinstall everything, leaving all drives unplugged. It was frustrating because I’d followed most of my usual setup steps, yet the issue resurfaced when I tried updating to 1903. I discovered via DiskPart that all disks were running MBR, which seems to be the core reason. Could this have been caused by the partitions I kept from the old drive? I’ve never seen an option to select the partition system during Windows installation. My previous SSD worked fine, but it might have used GPT before. Can I resolve this without a full reinstall? Also, how can I prevent this from happening again? I’m quite frustrated and confused right now. Thanks for any advice you can offer. Please let me know if you need more details. //Jonas
Hello, this might assist you. You could simply reinstall the system.
Hi, thanks for your feedback. I confirmed the approach through my own research. My system uses both a volume and a partition—my primary boot drive is C: and it holds all essential programs plus some games that didn’t fit on the older SATA SSD. I’ve set up overprovisioning, reserving 5% of the total space (50 GB out of 1 TB) for future use. Based on what I know, this setup shouldn’t prevent converting the drive to GPT, though I’d like to double-check. //Jonas
Open your UEFI settings and revert your configurations to their original state. Turn off UEFI to activate BIOS emulation. You’ll then be able to boot from MBR drives. If conversion isn’t possible, you’ll need to erase the drive and install a fresh OS. Make sure to set up your system BIOS/UEFI properly before installing any operating system, as changes can cause issues.
Hi Jonas, your question about BIOS emulation mode is interesting. There aren’t typically major downsides to using it, but some users report minor compatibility quirks or unexpected behavior. The BIOS/UEFI selection usually appears during the installation process, often in the setup wizard or during the initial boot sequence. If you decide to reinstall, double-check that all settings match your hardware and that you’re using the correct version for your system. It’s always a good idea to back up data before making changes.
Certainly. From your viewpoint, your setup seems to take longer to launch. Initially, everything functioned as expected without any adjustments. The issue doesn't appear after Windows installation; it arises during configuration of your motherboard and boot selection. It isn't related to the OS itself but rather how it's set up. Unless your hardware is brand new, verify these settings: the SATA controller should operate in AHCI mode (if using a SATA device). Ensure your primary drive uses the SATA-1 port (or SATA-0 if applicable), since this is where Windows installs the necessary bootloader. CSM should be turned off and UEFI enabled (the exact wording may vary by model). Delay Boot should remain at 0 seconds, Fast Boot activated, and Secure Boot must be turned on for security. Disable unused peripherals like extra Ethernet ports or non-essential controllers to minimize driver load and boost speed. Remember to configure the X.M.P profile for your RAM (or equivalent from AMD) to Profile 1. If you see options like "Windows 8 mode," treat it as UEFI configuration and adjust accordingly. When installing via USB, choose a drive labeled starting with "UEFI:" and confirm the boot order if available. Some boards automatically tweak settings; ensure they're correctly set before proceeding.
Hi once more, thanks for your feedback! Your previous SATA SSD was using AHCI mode, but now you're using an NVMe drive. The controller is configured as AHCI, and the SATA port is indeed one of those. It looks like one of the two possibilities might be the issue—perhaps I overlooked checking the CSM setting. I’m fairly confident everything is set to UEFI, though I’ll verify that later. Also, I assumed I selected the UEFI drive when prompted, but I might have made a mistake there. Just a note about the motherboard: your Asus Z170I Pro Gaming board seems quite modern in terms of features, though I’m planning an upgrade soon. "Relatively" up-to-date, but I’ll keep it that way.
Another idea that popped into my head is that the motherboard informs the OS setup (like Windows) that the first drive should be the SATA drive, not the NVMe one you plan to install. It seems the installation tool might be trying to place the boot partition on the MBR-formatted SATA drive instead of the GPT-formatted NVMe drive. A possible fix could be disconnecting the SATA cable from your HDD and retrying.
Microsoft now offers the MBR2GPT utility in the system32 directory for quick conversions, including partition reduction if needed. I tried it last week. Converting GPT to MBR is somewhat more involved, but manageable with a bootable Windows installer.
He merely stated his inability, which creates a scenario even more challenging than what would arise with a correctly set system.