Simply click Yes to confirm, then a pending operation is added. Then click on Apply to execute the conversion. I used Windows' DISKPART tool to identify the disk I want to convert. See moreYou can use MBR2GPT to: Convert any attached MBR-formatted system disk to the GPT partition format. MBR2GPT: Retrieving layout of disk. mbr2gpt /validate /disk:0 - success. Type mbr2gpt /convert /disk:[enter your disk number here] /allowFullOS and press Enter to begin the conversion. 1. 5) If it boots ok, you can remove old partition. Boot Windows install USB → When GUI loads, open terminal via Shift + F10. I can run this from WinPE but will it do what I want? My system is already a UEFI/GPY system, I just want to convert Disk 2 from MBR to GPT. If not specified, the. The MBR2GPT only supports converting MBR system disk to GPT. In the Properties Window, go to the “Volumes” tab. Select the disk you want to convert and then go to Actions menu –> All tasks –> Convert to GPT. Once it's converted make sure in the BIOS setup that UEFI is enabled, CSM/Legacy is disabled, Secure Boot enabled unless it interferes, Fast Boot disabled to be able to access the Boot Menu in time, later enable to speed up boot. 1/10, Windows Server 2003/2008/2012/2016 can use GPT disk to save data to. Then type “list disk” to display all the info of all the available disks installed in this computer. My hp Z620 Workstation is running Windows 10, version 1809. If conversion is successful the disk can only be booted in GPT mode. Non-boot GPT disks are supported on BIOS-only systems. This tool can be used to efficiently and losslessly convert MBR disks (for legacy BIOS) to GPT (for UEFI) on Windows 10. This option overrides this block and enables disk conversion while running in the full Windows environment. MBR2GPT: Validating layout, disk sector size is: 512. Do note that MBR2GPT can only be used from the Windows Preinstallation Environment. Sort by: Open comment sort options. exe can only run from Windows PE and is blocked from running in full Windows. or. exe to perform the disk validation and to proceed with the conversion if all validation tests pass. MBR2GPT: Trying to shrink the OS partition. #5. This will convert MBR to GPT. в—Џ MBR2GPT cannot find OS partition. You can access the command prompt by pressing Shift + F10 at the screen asing for language. To identify the disk drive to reformat, type list disk and press Enter key. When using this tool, the conversion process. Several techniques are available to access one of the superior experiences in using MBR2GPT. Converting from MBR to GPT is not entirely without risk, and it's possible that your hardware might not support GPT. You can't use the tool to convert non-system disks from. Type: exit. Instead, reboot your system into your BIOS Setup. MBR2GPT: Retrieving layout of disk . Steps to convert mbr to gpt in Windows Server 2012 (R2) with MBR2GPT cmd: Step 1: Download Windows Server 2019 ISO and create bootable DVD or USB flash drive with Windows built-in or third-party tool. exe to perform the disk validation and to proceed with the conversion if all validation tests pass. Run the fix windows boot problems utility from the Macrium Reflect restore menu. d. If you use it to convert a data disk, you can receive an error: MBR2GPT cannot find OS. I am not sure how that happened since when I installed windows on the newly built PC I only had my boot drive physically plugged into the MOBO. exeというcmdに似た画面が開くのでここにlist diskとコマンド。 GPTの列に＊マークがあればGPT、なければMBR。 GPTに変換できるかチェック 変換したいディスクをdisk:0とする（ディスクは上記で調べる）。 cmdで以下をコマンド。 mbr2gpt /validate /disk:0. Press Enter, and you are done. Share. How to convert MBR to GPT in Windows 10 with MBR2GPT command: Back up your system with Windows native or third party software in case of. Reply. After this i needed to do the mbr2gpt convert so as to enable secure boot, which i used available software which claims to be able to do the convert whilst still logged into windows 10. The selected disk has an MBR partition table. After you have run the MBR2GPT Validate and it failed, open the "setupact. Open the Run dialog (Windows key + R) and type diskmgmt. I further agree that a system's MBR-partitioned secondary drive that has been used for storage and DOES NOT contain the Win 10 OS (as apparently in the OP's case) cannot be converted to the GPT-partitioning scheme via the MBR2GPT disk conversion tool. /allowFullOS - Allows the tool to be used from the full Windows environment. I read somewhere I should use switch from BIOS to UEFI to boot from USB and that I should use the tool mbr2gpt for that, since there's no UEFI option in the BIOS settings. EXE /convert /allowfullos MBR2GPT will now attempt to convert the default book disk. Type select disk 1 to tell diskpart you’d like to perform an action on a disk. Try this: Run CMD as Admin and run diskpart. Reboot the computer and run mbr2gpt /validate. If conversion is successful the disk can only be booted in GPT mode. Download and launch EaseUS Partition Master on your computer. Mbr2gpt. MBR2GPT. The only limit found in the specs is that the EFI must reside in the first 2. There is no MSR partition. As an alternate approach, you can use the MBR2GPT. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is:. Type select disk * (replace * with the disk number that you want to remove partitions on) and hit Enter. It has to create an EFI partition so original drive can only have three. MBR2GPT: Attempting to validate disk 1. exe through the command prompt. You can choose the proper one to. Step 2. Click on the Disk Management option on the left side in the Storage section. exe is a little complex to use. which is a M. 1) You cannot use mbr2gpt if 4 MBR partitions to start with - from log you can see it creates EFI first then does conversion to GPT. Unlike older methods requiring a backup of your data and reinstalling Windows, the MBR2GPT tool makes it easy to change the partition style quickly. 1 on, without losing Linux, and normally boot both OS as I used to. 2021-09-14 16:08:24, Info MBR2GPT was explicitly asked to run in full OS mode. EXE converts a disk from Master Boot Record (MBR) to GUID Partition Table (GPT) partition style without modifying or deleting data on the disk. msc. GPTに変換できるかチェック. Next, in the command line, enter: REAGENTC /SetOSImage /Path C:Win81-RecoveryINSTALL. Hopefully you'll see a "Validation completed successfully" message. In Windows XP 64-bit, GPT disk can be used for data storage instead of system installation. (These commands can be copy and pasted all at one time:) list disk. The command "mbr2gpt /validate /disk:0" checks whether a conversion from MBR to GPT is possible and with. GPT supports Cyclic Redundancy Check (CRC) for the integrity of data, while. Windows has included a utility since the 1703 release, called MBR2GPT. EXE /convert /disk:0 /allowfullos. Your inability to update Windows has nothing to do with Legacy or UEFI mode based on those logs. MBR2GPT: Attempting to validate disk 0 . Local time: 07:34 PM. A ferramenta é executada a partir de um prompt de comando do Windows Preinstallation Environment (Windows PE), mas também pode ser executada a partir do. The process fails repeatedly, returning the following error: MBR2GPT will now attempt to convert the default book disk. Windows will recognize your other HDD. For details, see Convert MBR partition to GPT. These changes cannot be undone! MBR2GPT: Attempting to convert disk 1 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes Cannot find OS partition(s) for disk 1Namely, MBR can only handle four primary partitions and 2TB of drive space. exe in both active mode and WindowsPE. As mentioned before, the MBR2GPT. 7) if it fails, you can restore image backup of partition. To resolve: Windows 10 installation media → install on another PC → Save ISO. If the utility returns “MBR2GPT: Validation completed successfully,” then you know you are ready for the. Converts a disk from MBR to GPT partitioning without modifying or deleting data on the disk. Run mbr2gpt /convert /disk:<disk number> /allowFullOS. log文件内容如下. Also, MBR only supports 4 partitions, so you cannot have more than 3 on the drive when using it. After your system restart, press your BIOS/UEFI entry key. These changes cannot be undone!By default, MBR2GPT. Under the new group, add the Restart Computer task sequence step. Apply MBR2GPT. It is not automated. PS C:\Users\Marcelo Pires> mbr2gpt /validate /allowFullOS . By default, this tool can only be used from the Windows Preinstallation Environment. MBR2GPT. a. ; Click on Update & Security. Not to Legacy only + IDE. As long as your disk satisfies the requirements, it'll convert the disk from MBR to GPT without data loss. If you want to convert a MBR disk with only data to GPT, you have to run third party software. Note: Disk Management can only convert data disk instead of OS disk to GPT with certain kind of conditions listed in the front of this article (the same ones as mbr2gpt convert cmd). 0 TB Disk Drive). EXE tool to convert the MBR disk to the GPT partition format. EXE /convert /disk:0 /allowfullos MBR2GPT will now attempt to convert disk 0. ; Click on Recovery. Only when you see the partition style is GUID Partition Table, you can upgrade to Windows 11. I think the isuue you have is the system ( active) partition is on disk0. If conversion is successful the disk can only be booted in GPT mode. Click “Apply” to commit the pending operation. You can begin using the MBR2GPT. cmdで以下をコマンド。. 4. Should I use this capability to convert the partition to GPT or are there risks to doing this. Mbr2gpt allows converting only system disks (disks with installed OS), only with 2 partitions, without logical partitions, and so on. Change the boot type to UEFI mode instead of Legacy Mode or. GPT (GUID Partition Table) disk has many advantages than MBR (Master Boot Record) disk, for example: overcome the maximum 2TB space and 4 Primary partitions restriction. EXE" to convert the VM disk from MBR to GPT. The. When I did this, I was unable to see the drives. type: diskpart. Add sentence saying if drive already had 4 primary partitions, you need to delete the System Reserved Partition first. 2. Nov 4, 2022 at 10:51. 4. Although MBR2GPT is easy to use, your disk partition configuration must meet the requirements below. Jetzt habe ich gelesen, man kann dies mit dem Boardmittel "mbr2gpt. 3. Ahva intends to add the hard disk to a storage pool. Step 2: Click the Apply button to execute. I open a command line in Windows and run: mbr2gpt /validate mbr2gpt /convert. Compatibility: Best used for older systems. As an alternate approach, you can use the MBR2GPT. MBR2GPT: Retrieving layout of disk. If you want to upgrade to Windows 11, you should convert the MBR system disk to GPT, so many users want to use MBR2GPT for Windows 11. In this article. Step 4: Right-click the Windows Start screen button and select Command Prompt (Admin) on the desktop. Blackskull . Type the following command to convert the system drive to GPT from MBR and press Enter: mbr2gpt /convert. Steps to convert MBR to GPT in Windows Server 2012 R2 without losing data: Download NIUBI Partition Editor, right click the front of the MBR disk and select " Convert to GPT Disk ". Cannot find room for the EFI system partition. . mbr2gpt /convert. Use /allowFullOS to override. I can't boot from the USB. These changes cannot be undone! MBR2GPT: Attempting to convert disk 2 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes MBR2GPT: Trying to shrink the OS partition MBR2GPT: Creating the EFI system partition Cannot create. mbr2gt is very finnicky. 6. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes Open your computer normally. Try the MBR2GPT conversion tool. Select the unallocated space and click Next. Before attempting the convert i deleted the recovery partition as you cannot do the convert if you have more than 3 separate partitions shown in Disk Management. I'm working on a new Windows 10 build and I have been having some issues. Being a command line utility, MBR2GPT. MBR2GPT can be performed with or without data loss: Convert Windows 10 from Legacy BIOS to UEFI without Data Loss Convert MBR Disk to GPT Disk in Windows 10 This is an alternative option: Once the BIOS is booting UEFI then a clean install Windows will be GPT. Either you didn't properly understand the tutorial, or it's a disastrously wrong one. With NIUBI Partition Editor,. before choosing the disk which you want to change. Right-click the disk that you need to convert (here is system disk) and choose “Convert to GPT”. The MBR2GPT tool is used to convert disk 0. First, we cannot use the MBR2GPT to convert non-system disks from MBR to GPT, so you don’t need to consider using the mbr2gpt on ALL of your Harddisks. 2. Use Disk Management to convert MBR to GPT (Need to Delete Partitions) Tip 3. Let’s see how to use the MBR2GPT tool to convert from MBR to GPT drive: Step 1: Firstly, you would need to obtain the disk number. Use the command detail partition to see if it's marked as "Active No", and if so type the Active command. Then disconnect drive 0 and check drive 1 boots ok. In a while, the conversion will be completed. The author has 3 plus an extended partition. The output should look similar to this: C:WindowsSystem32> mbr2gpt /convert /allowFullOS MBR2GPT will now attempt to convert the default book disk. – harrymc. 3. Shut down, detach drive 0 and drive 2 (SATA or power cable), on BIOS select drive 1 as boot priority and try to boot. Step 3. Right-click on each partition on the disk you want to convert and select " Delete Volume " to clean the disk. Next, copy and paste this command in Command Prompt window, and then hit Enter. I was then able to use mbr2gpt /convert and the conversion worked! Nothing was lost (other than a lot of hair), and I checked the system with PC Health and got confirmation - the system requirements for Windows 11 are now met!. By having built your Rescue Media on WinPE/RE 10, you will have MBR2GPT available in your. After converting, restart your system and change your motherboard firmware. See the below screenshot. (All operations before clicking Apply only work in. Note: Since the existing MBR system partition is in use while running the full Windows environment, it can't be reused. You can also choose to run the MBR2GPT. /allowFullOS - Allows the tool to be used from the full Windows environment. Make a disk image and save to an external disk before you try anything. 5. hold down the shift key while clicking power > restart > click troubleshoot > click command prompt. Boot system selected is for SSd. If you don’t specify the disk number, it will choose disk 0 by default. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0. bcdboot C:Windows /s C: /f BIOS. The mbr2gpt tool can be used to convert the partition table both in Windows PE (Windows Preinstallation. exe /disk:4 /convert /allowFullOS. exe (provided in Windows 10) With the modded BIOS and the drive set to GPT, I was able to boot Windows 10 from the M. Use /allowFullOS to override. - Use a boot disk with MBR2GPT. MBR2GPT: Validating layout, disk sector size is: 512 bytes. The Mbr2gpt tool has many restrictions. MBR2GPT: Retrieving layout of disk. C:WINDOWSsystem32>mbr2gpt. ) If you do everything manually, you can skip the mbr2gpt step – use AOMEI to convert the disk to GPT, then repartition, then directly create an EFI System Partition and use a Windows ISO to populate it using bcdboot. C:\WINDOWS\system32>mbr2gpt /convert ERROR: MBR2GPT can only be used from the Windows Preinstallation Environment. MBR2GPT: Attempting to validate disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes Disk layout validation failed for disk 0 . –So I used the command: mbr2gpt /convert /disk:0 (it is the only disk on the system) here is my output: MBR2GPT: attempting to convert disk 0 MBR2GPT: retrieving layout of disk MBR2GPT: validating layout, disk sector size is: 512 bytes MBR2GPT: backing up the system partition MBR2GPT: creating the EFI system partition MBR2GPT: installing the. exe. One of the other requirements is not to have any extended partitions, look to the primary rule of only having 3 partitions, on the reason why that's the case. exe is a new built-in Windows 10 console tool that allows you to convert a disk with the MBR (Master Boot Record) partition table to a GPT (GUID Partition Table) without data loss and without the need to delete existing partition. Therefore you can take advantage of all of the features offered by GPT disks even though your motherboard only supports BIOS mode. It can only support hard drives up to 2 TB and supports up to 4 primary partitions. As mentioned before, the MBR2GPT. Go to Disk Converter, select "Convert MBR to GPT" and click "Next" to continue. mbr2gpt /convert /disk:0 - success. wim" REM NOTE: The following can only be run from the. The only item available in the "Troubleshoot" menu is "UEFI Firmware settings. The selected disk has an MBR partition table. Regardless of the tool you use, you will have to reboot to switch from BIOS to UEFI after you've run the tool. Sep 28, 2021 at 19:36. This is optional. EXE convertit un disque d'enregistrement de démarrage principal (MBR) en un style de table de partition GUID (GPT) sans modifier ou supprimer les données contenues sur le disque. As bobkn suggested, so do I, use mbr2gpt on her drive and then upgrade to Win 11. If conversion is successful the disk can only be booted in GPT mode. Just like the MBR2GPT tool, Gptgen is capable to convert hard disk in a non-destructive way. Use /allowFullOS to override. mbr2gpt /validate /disk: 0 /allowFullOS. Note: When Windows detects a non-initialized disk, select the Disk, choose GPT, and click OK. Add a step to restart the computer to Windows PE before the. MBR2GPT: Retrieving layout of disk. Boot into Windows. Previous methods are considered a destructive conversion as. mbr2gpt /validate /disk:0 /allowFullOS . - Boot from Win 10 or Win 11 installation drive and launch the CMD window. Click on OK to confirm this change. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes MBR2GPT: Trying to shrink the system partition MBR2GPT: Trying to shrink the OS partition MBR2GPT:. b) bcdedit /enum. 4) this is major: if you reverse a conversion to GPT back to MBR, everything will remain broken until AFTER you delete the EFI partition that the GPT conversion created. diskpart. That is, it will not work for a data disk that does not have an operating system installed. C:\WINDOWS\system32>mbr2gpt. EXE appears to be an internal tool to do this. You just need to wait until MiniTool Partition Wizard opens automatically. MBR2GPT. OStensibly), higher drive capacities, improved update methods and driver support, as well as 64-bit mode (where BIOS is only 16-bit). Use /allowFullOS to override. Note that this tool is only available in Windows 10 version 1703 onwards. EXE converts a disk from Master Boot Record (MBR) to GUID Partition Table (GPT) partition style without modifying or deleting data on the disk. I read a bit about it, and it seems to not work because disk 0 isnt a system disk, but in my. mbr2gpt. 3. 4. MBR2GPT requirements are simple, there can only be 3 partitions (basically), in order to use it. replied to TammerAb Oct 07 2021 12:14 PM - edited. Select the target MBR disk that you tend to convert to GPT, and click "Convert" to start the conversion. Click Apply on top left to execute, done. With this condition, the task sequence only runs these steps on BIOS devices. MBR2GPT: Validating layout, disk sector size is: 512 bytes. これを使用して、OS・データはそのままでCドライブをGPTへ変換できました。. Boot your Rescue Media. Click Install Now button. 2. 3. If conversion is successful the disk can only be booted in GPT mode. MBR2GPT will now attempt to convert the default book disk. 1) The internal command line application MBR2GPT. It can only be used after bcdboot. In case you want to make a conversion of MBR2GPT, you can make use of professional software. If all goes well, you should see a successful message. When choosing an installation type, select Custom. Select the target MBR disk that you tend to convert to GPT, and click "Convert" to start the conversion. リターン コード. If all goes well, you should see a successful message. Step 1. For details, see Convert MBR partition to GPT. By default, MBR2GPT. If you are converting an OS disk, you will be asked to enable UEFI Boot mode from BIOS. run mbr2gpt command first, reboot into BIOS, change boot mode from legacy/CSM to UEFI, change boot order, so windows boot manager is first, boot into windows. 2. The launch of Windows 11 is 6 months away, you have plenty of time, I have seen so many people loose all their data converting the drive from MBR to GPT, honestly the only successful method is to backup all your data, then clean install Windows 10 from a bootable USB and then re-install all your software, it is a big job. Reply. msc. exe is blocked unless it is run from Windows PE. This will open the Disk Management console. It runs under Parallels, on a MacBook Pro. How to Use MBR2GPT. In the Command Prompt, type list disk and hit Enter. The only issue with it this - It needs to be able to shrink 600MB or so from the end of the drive, and be able to create a new partition. ; Open Disk Manager. MBR2GPT: Validating layout, disk. Click the Volumes tab, here you could see your disk's partition style. MBR2GPT will now attempt to convert the default book disk. exe can only run from Windows PE and is blocked from running in full Windows. Make sure you carefully follow the guide below. I asked, because different 'reasons' can lead to vastly different answers. If conversion is successful the disk can only be booted in GPT mode. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT:. 【以下の条件が必須. MBR2GPT: Retrieving layout of disk. The mbr2gpt tool can be used to convert the partition table both in Windows PE (Windows Preinstallation. If conversion is successful the disk can only be booted in GPT mode. exe and the conversion was completed successfully. Convert MBR to GPT using Diskpart: Backup all your data and then use the DISKPART. MBR is just as good as GPT. but on restarting diskmgmt showed my c drive was still mbr. 2. Step 2. But keep a disk image backup, just in case. However, this happened: C:WINDOWSsystem32>MBR2GPT. Right-click “ My Computer/This PC ” -->” Manage ”-->” Disk Management ”. Edit it to select the correct disk #. 版本：win10 1703 当前主机非PE. The MBR2GPT. This way can ensure the consistency of the data and the operating system can start normally after the conversion. > mbr2gpt /convert /disk:0 MBR2GPT will now attempt to convert disk 0. GPT supports much more and is only limited by the OS. Type convert gpt and press Enter key. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is:. it's a pain. Step 3. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 MBR2GPT: Retrieving layout of disk MBR2GPT: Validating layout, disk sector size is: 512 bytes MBR2GPT: Trying to shrink the system partition MBR2GPT: Trying. Note: Disk Management can only convert empty disk to gpt in Windows computers. Right-click on the target disk, and select " Convert to GPT Disk ". Select disk n (n is number of drive with C:, usually 0) clean (wipes drive completely) convert gpt. If you initialize a 4TB disk. 0 Likes . WinPE_X86_PSmountoot2. On EFI systems, Windows can only installed on GPT disks. EXE 可将磁盘从主启动记录 (MBR) 转换为 GUID 分区表，. You can use MBR2GPT to: Convert any attached MBR-formatted system disk to the GPT partition format. Then you can swap drives and boot into drive 0 and run mbr2gpt on that drive. mbr2gpt /validate - failed to retrieve geometry for disk -1. If not specified, the system disk is processed. 1. When I tried mbr2gpt /validate /disk:2 I get ERROR: MBR2GPT can only be used from the Windows Preinstallation Environment. exe and convert it to MBR. Windows 10はバージョン1703以降で、ディスクパーティション形式をMBRからGPTへ変換する MBR2GPT. Jul 30, 2019 @ 1:08pm First make sure your BIOS is set to UEFI and AHCI. The drive will appear as a single area of unallocated space. “MBR2GPT cannot find OS” when converting the data disk. Nepal's Kusunda language has no known origin and a number of quirks, like no words for "yes" or "no". . In addition, you can also convert GPT to MBR without data loss. Supported drive size: While it can read drives above 2 TB, anything over 2 TB will be unusable. We will use the official Microsoft tool "MBR2GPT. exe – это встроенная консольная утилита Windows 10, которая позволяет сконвертировать диск с таблицей разделов MBR (Master Boot Record) в таблицу GPT (GUID Partition Table) без потери данных и без необходимости. exe is a new built-in Windows 10 console tool that allows you to convert a disk with the MBR (Master Boot Record) partition table to a GPT (GUID Partition Table) without data loss and without the need to delete existing partition. I. You need to change your firmware to boot to UEFI mode. Open cmd in admin mode. exe to perform only the disk validation steps and report whether the disk is eligible for conversion. You can also convert the partition table on Linux after having a working ESP prepared on. These changes cannot be undone! MBR2GPT: Attempting to convert disk 0 . Supported drive size: While it can read drives above 2 TB, anything over 2 TB will be unusable. Cannot find room for. msc into Run, and click/tap on OK to open Disk Management. Windows Command Prompt. WIM /Index 1. However, you can use An attribute to allow the existing partition to run the MBR2GPT tool. #2. Try the MBR2GPT conversion tool. Completely erase (clean) disk 1 and convert it to GPT. Also: In der Suche mbr2gpt. Here is how you create your own USB Key Windows 10 installation media. It has two disk drives in it. 2. C:WINDOWSsystem32>mbr2gpt. exe. Restart your computer. delete system partition first. In the command prompt window, input mbr2gpt /disk:0 /convert /allowFullOS and then press Enter. 「Validation completed successfully」と出ればOK。. Step 2: Step 2: Click Apply to execute this conversion. Boot from windows bootable image. type: mbr2gpt /validate.