Updated by

Tracy King

Updated on April 28, 2024

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⏳Duration: 3-5 minutes
?Goal: Resolve the MBR2GPT error of not finding the OS partition in Windows
?Supported Systems: All Windows systems
?Who Will Need It: Windows beginners and non-technical users

Are you encountering the frustrating 'MBR2GPT cannot find OS partition' error while trying to convert your disk from MBR to GPT? This issue usually arises when using the MBR2GPT tool to change the disk layout on your computer. But worry not! In this article, we'll walk you through effective solutions and provide straightforward tutorials to assist you in fixing the 'MBR2GPT cannot find OS partition' error like a pro. Let's dive in and permanently resolve this problem!

MBR2GPT cannot find OS partition error

What to Do When Windows Reports 'MBR2GPT Failed to Find OS Partition' Error

If you encounter the 'MBR2GPT cannot find OS partition' error, refrain from using the command line mbr2gpt /convert /disk:* /allowfullOS. It is crucial to stay calm and avoid utilizing the command line further when this error occurs. Instead, we advise you to follow the provided workaround solutions to efficiently address this issue.

Below, we have outlined the solutions, accompanied by their respective complexity levels and estimated durations, to assist you in selecting the most appropriate approach for your circumstances.

Procedure Complexity Level Duration

Fix MBR2GPT Cannot Find OS Partition Error

Complex 5-10 minutes
Convert Disk from MBR to GPT Moderate 3-5 minutes

Please note that if you have encountered a similar error, exercise caution while implementing these solutions. Now, let's examine each solution in depth to resolve the 'MBR2GPT failed to find OS partition' error and restore your system to normal operation.

Guide 1: Resolve Disk Error Leading to the 'MBR2GPT Cannot Find OS Partition' Issue

The "MBR2GPT cannot find OS partition" error during the disk conversion process can stem from various reasons. To rectify this issue, please adhere to the solutions provided below:

#1. Switch the Boot Mode from Legacy to UEFI

Firstly, you need to switch your computer's boot mode from Legacy to UEFI, as the transition from MBR to GPT requires UEFI. Here's how to do it:

Step 1: Restart your computer.

Step 2: Press and hold F2 to enter the BIOS Setup.

Step 3: Use the arrow keys to select the "Boot" tab.

Step 4: Choose "UEFI" in the "UEFI/BIOS Boot Mode". Press Enter.

Change Boot mode to uefi

#2. Run SFC/Scannow to Fix Existing System File Errors

Corrupted system files can disrupt the MBR2GPT conversion process. To rectify any system file errors, follow these steps:

Step 1. Log in as an administrator and open the Command Prompt. To do this, right-click the Start button and select "Command Prompt (Admin)."

Step 2. Type the command "sfc /scannow" in the Command Prompt window.

Run SFC command

Step 3. Wait for the System File Checker (SFC) tool to scan your system and repair any corrupted files it finds.

To ensure a successful scan and repair process, kindly follow the instructions to navigate through the Command Prompt steps.

If this method resolves the error for you, share your experience to assist more individuals encountering the "MBR2GPT unable to find the OS partition" issue online.

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#3. Check the Status of the Target Disk and Verify Its Health

确保在转换前目标磁盘处于良好状态是很重要的。请按照以下步骤操作:

在开始磁盘转换之前,确保目标磁盘处于良好状态至关重要。请执行以下操作:

Step 1. Launch Windows' Disk Management program. Right-click the Start button and select "Disk Management."

Step 2. Check if the destination disk appears in Disk Management and note the assigned drive letter.

Check disk state in Disk Management

Step 3. To make sure the disk can be accessed without issues, attempt to open it.

If the disk is functioning properly, you can proceed to the next step and complete the disk conversion successfully.

Guide 2: Convert MBR to GPT using MBR2GPT Alternative or MBR2GPT Command

Now, let's examine two methods to successfully convert your MBR disk to GPT. Choose the method based on your preference and level of expertise.

Method 1: Convert MBR to GPT using MBR2GPT Alternative Tool - tools Partition Master

For Windows users in search of a reliable and user-friendly tool to convert their disk from MBR to GPT, we highly recommend Partition Master. This software boasts a convenient "Convert to GPT" feature, enabling you to alter the partition style of your target disk without any data loss or damage.

Pros and Cons of Partition Master Tool:

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Pros Cons
  • Suitable for all levels of Windows users, including beginners.
  • Guarantees a smooth and secure transition from MBR to GPT.
  • Your existing data remains untouched during the conversion process.
You will need to purchase the paid version of Partition Master after the free trial period.

Why we recommend Partition Master:

tools Partition Master is an excellent choice because of its simplicity and efficiency. It removes the complexities often encountered in disk conversion, making it the perfect solution for users who prefer a straightforward method.

To start, download and test Partition Master from their official website. Follow these steps:

Step 1. Download and launch Partition Master on your computer.

Step 2. Proceed to Disk Converter and choose "Convert MBR to GPT," then click "Next" to proceed.

convert MBR to GPT - 1

Step 3. Select the target MBR disk that you want to convert to GPT, and click "Convert" to start the process.

convert MBR to GPT - 2

Please feel free to share this method to assist more of your friends who are searching for an efficient solution to convert a disk from MBR to GPT without data loss online:

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Method 2: Convert MBR to GPT using the MBR2GPT Command Line Tool

MBR2GPT offers a straightforward approach for experienced users with command line operations and Windows 10 version 1703 or later to convert their MBR disk to GPT. It's crucial to weigh both the advantages and disadvantages of using this command-line tool.

Pros and Cons of MBR2GPT Command Lines

Pros: Cons:
  • Native Windows utility: MBR2GPT is built-in with Windows 10 version 1703 and later, eliminating the need for additional software installation.
  • Advanced control: Experienced users who are familiar with command-line operations can have greater control over the conversion process.
  • Windows version requirement: MBR2GPT is only available on Windows 10 version 1703 and later. If you are using an older Windows version, then using tools like Partition Master is your best option to address the issue.
  • Difficulty level: MBR2GPT command lines can be quite challenging for beginners to understand.

Steps to Convert MBR to GPT using MBR2GPT Command Line

If your Windows requirements align and you're comfortable with interpreting command lines, follow these steps:

Step 1. Open Command Prompt and choose "Run as administrator."

Step 2. In the Command Prompt window, type the following command: mbr2gpt /convert /disk: /allowfullOS.

Step 3. Allow the process to complete. It may take a few minutes; do not turn it off during this process.

mbr2gpt command

What Causes the 'MBR2GPT Cannot Find OS Partition' Error and How to Prevent It

Here are some common reasons for the 'MBR2GPT Failed to Find OS Partition' error and how you can prevent these issues: 1. **Incorrect Disk Selection**: Ensure that you are converting the correct disk containing the operating system. Sometimes, users might mistakenly choose a different disk without an OS partition. **Solution**: Double-check the disk selection in the MBR2GPT utility and verify that it's the one with your installed operating system. 2. **Inadequate Disk Space**: The operating system partition might not have enough free space for the conversion process. **Solution**: Free up disk space by deleting unnecessary files, uninstalling programs, or moving data to an external storage device before attempting the conversion. 3. **Mixed Partition Styles**: If your disk contains both MBR and GPT partitions, the conversion may fail. **Solution**: Back up your data, delete the GPT partitions, and then try the conversion again. 4. **Running the Tool from the Wrong Environment**: MBR2GPT needs to be executed in Windows Setup or Windows PE (Preinstallation Environment). **Solution**: Boot into Windows Setup (using installation media) or create a Windows PE environment to run the MBR2GPT command. 5. **OS Compatibility**: The operating system version might not support the MBR2GPT tool. **Solution**: Make sure you're using Windows 10 version 1703 or later, as earlier versions don't support this feature. 6. **Protected System Partition**: Some system reserved partitions might be protected, preventing modification. **Solution**: Use the `diskpart` utility to temporarily disable the protection, then run MBR2GPT, and re-enable the protection after the conversion. 7. **Third-Party Disk Management Tools**: The presence of third-party disk management software could interfere with the conversion. **Solution**: Temporarily uninstall any third-party disk management tools and try the conversion again. 8. **Hardware or Firmware Issues**: In rare cases, the error might be due to firmware bugs or hardware incompatibilities. **Solution**: Check for firmware updates for your motherboard and ensure your system meets the requirements for GPT disks. Always back up important data before attempting any disk conversions, and if the issue persists, consult Microsoft support or a professional technician for further assistance.

Possible Causes of the 'MBR2GPT Cannot Find OS Partition' Error

The "MBR2GPT cannot find OS partition" error can occur due to several reasons, such as:

  • Disk errors: Existing disk errors, such as damaged partitions or file system issues, can prevent the MBR2GPT utility from detecting the OS partition.
  • Incompatible boot mode: MBR2GPT requires the correct boot mode for a successful conversion. If your computer is set to an incompatible mode, like Legacy (MBR) for a GPT conversion, the error might occur.
  • Missing system files: If crucial system files are absent or corrupted, MBR2GPT might fail to identify the OS partition during the conversion process.

"Practical Tips to Avoid the 'MBR2GPT Cannot Find OS Partition' Error"

To avoid encountering the "MBR2GPT failed to find OS partition" error, consider implementing these suggestions:

  • ✔️Set the compatible boot mode: Make sure your computer is set to the appropriate boot mode that corresponds with the desired partition style. For converting to GPT, set the boot mode to UEFI-GPT; for MBR conversion, set it to Legacy-MBR. Confirm and adjust this setting in your BIOS/UEFI configuration.
  • ✔️Fix system file errors promptly: Regularly scan your system for any damaged or missing system files. Utilize tools like the System File Checker (SFC) utility to identify and repair these errors, maintaining a healthy operating system.
  • ✔️Maintain disk health: Check your disk for errors consistently and address any issues promptly. Use disk management utilities or third-party disk-checking tools to scan and correct disk errors, ensuring a smooth conversion process.
  • ✔️Backup your data: Prior to attempting any disk conversion, it's wise to back up your important data. This precautionary measure protects your files from potential errors or data loss during the conversion process.

By adhering to these practical guidelines, you can significantly reduce the likelihood of encountering the 'MBR2GPT failed to find OS partition' error and ensure a more seamless disk conversion process.

Conclusion

In conclusion, if you encounter the 'MBR2GPT cannot find OS partition' error, it is essential to refrain from using the MBR2GPT command and instead adhere to the methods outlined in this article to effectively address the issue.

  • For novices or those seeking an user-friendly option, Partition Master is recommended as a dependable alternative tool.
  • Experienced users can employ the MBR2GPT command lines, provided they meet the necessary Windows version requirement.

Remember to implement preventative measures like setting the appropriate boot mode, promptly addressing system file errors, maintaining disk health, and backing up your data. By adhering to these guidelines, you can resolve the error and successfully complete the disk conversion process.

FAQs About "MBR2GPT Cannot Find OS Partition" Issue

Here are a few questions that might assist you in addressing and resolving the issue where MBR2GPT fails to find the OS partition error:

< b > 1. Can I use MBR2GPT to convert a non-OS disk?

No, the MBR2GPT utility is designed to convert only the disk that contains the operating system (OS) from Master Boot Record (MBR) to GUID Partition Table (GPT). It is not intended for converting non-OS disks.

2. What to do if MBR2GPT reports disk layout validation failed?

If MBR2GPT reports a "disk layout validation failed" error, ensure the disk satisfies the conversion prerequisites and is not locked or in use. Run disk utilities such as chkdsk to check for errors, and consider backing up your data prior to converting the disk to GPT or performing a clean OS installation, if needed.

3. What is the best alternative software to MBR2GPT?

One of the top alternatives to MBR2GPT software is Partition Master, which provides a user-friendly interface and a convenient "Convert to GPT" function for smooth disk conversion.