How to fix Windows upgrade error 0x800702A9?


Issue: How to fix Windows upgrade error 0x800702A9?

Hello. I have been trying to upgrade my PC from Windows 8.1 to Windows 10 using the Microsoft upgrade page. It always fails around 75% and then reverts the page with an error 0x800702A9 “Windows 10 Installation has failed.” I have tried it multiple times, but the same thing happens. Any suggestions would be appreciated.

Solved Answer

Windows is one of the most popular operating systems in the world created by Microsoft. It is liked by many for its customization abilities, user-friendly interface, and automatic, built-in troubleshooting options. However, it still does not come without any errors. Sometimes users encounter issues that cannot be fixed automatically.

Often, users that have older versions of Windows want to upgrade to the newer version. Using an outdated version is not only impractical but dangerous as well. Microsoft stopped supporting Windows 7 in 2020,[1] which means that the machines with that OS will no longer receive security, stability, and other updates.

While at first the upgrade process of older Windows versions to Windows 10 seems like an easy task, for many it may become a headache. How easy the upgrading process is going to be, depends on the age of the device, compatibility, the system requirements, and the upgrade method.

Before starting the process or upgrading, we suggest you take a few precautionary steps. You should backup all the important files on your system, such as pictures, music, videos, documents, and other data. You can keep your files during the upgrading, and you will most likely not need backups, but it is recommended backing data regardless, in case something goes wrong. Simply take an external storage device, such as a USB stick, SSD, or a DVD, and copy all your files over.

How to fix Windows upgrade error 0x800702A9?

Most often, error0x800702A9 indicates that Windows is missing some files required by Windows Update to perform the upgrade. When an error code such as this appears, Windows cannot finish upgrading the operating system. Other common reasons may include incorrect user input and accidentally deleted files from the registry[2] that now cause system malfunctions.

Troubleshooting manually could take a while because it is unclear what is causing the issue, so you can try using an automatic solution ReimageMac Washing Machine X9 to avoid going through all of the possibilities. The repair tool can identify the damaged system components, fix BSODs,[3] and registry issues by scanning the system. This software could also be used to free up space by clearing cookies and cache, which should boost the device's performance.

Below you will find a few manual methods that could fix the Windows upgrade error 0x800702A9 and let you update your system. Note that this will take a while, so please follow all of the steps very carefully:

Method 1. Update Windows

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To repair damaged system, you have to purchase the licensed version of Reimage Reimage.
  • Open your Start menu and type in Settings
  • Choose Update & Security and then Windows Update

Update Windows

  • Click the Check for updates button, and install the available updates

Method 2. Repair corrupted files

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To repair damaged system, you have to purchase the licensed version of Reimage Reimage.

Use Command Prompt commands to repair system file corruption:

  • Open Command Prompt as administrator
  • Use the following command and press Enter:
    sfc /scannow

Repair corrupted files

  • Reboot your system
  • If SFC returned an error, then use the following command lines, pressing Enter after each:
    DISM /Online /Cleanup-Image /CheckHealth
    DISM /Online /Cleanup-Image /ScanHealth
    DISM /Online /Cleanup-Image /RestoreHealth

Method 3. Check Disk

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To repair damaged system, you have to purchase the licensed version of Reimage Reimage.

Ensure that your disk is not damaged. You can perform checks using Administrative Command Prompt:

  • If you are using an HDD as your main driver (where your operating system is installed – C: by default), use the following command and press Enter:
    chkdsk c: /f

Check Disk

  • If you are using SSD, use this command:
    chkdsk c: /f /r /x
  • If you receive an error, type in Y and hit Enter
  • Restart your device to perform the check

Method 4. Uninstall non-Microsoft antivirus software

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To repair damaged system, you have to purchase the licensed version of Reimage Reimage.
  • Select Start, then select Settings
  • Go to Apps > Apps & features

Uninstall non-Microsoft antivirus software

  • Select the app you want to remove, and then click Uninstall

Method 5. Perform a Clean Installation

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To repair damaged system, you have to purchase the licensed version of Reimage Reimage.

Performing a clean install wipes out data from PC, hence please create back up before you proceed

If all else fails and you can't even reset your Windows computer, you can reinstall the OS entirely. You won't even need an activation number or any proof of purchase, either. Just make sure you have more than 4GB of space available, as that's how much space the file you'll download takes up. Here's how to reinstall Windows 10:

  • Download the ISO file
  • Select Create installation media for another PC and click Next
  • Select ISO file and click Next
  • Click Finish
  • Open the Windows ISO file you downloaded

Perform a Clean Installation

  • Open Setup and click Next
  • Click Accept (Be prepared to wait; this next part may take a while)
  • Click Install
  • Wait for your system to restart and install Windows

You might also be interested in these topics:

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This patented repair process uses a database of 25 million components that can replace any damaged or missing file on user's computer.
To repair damaged system, you have to purchase the licensed version of Reimage malware removal tool.

Prevent websites, ISP, and other parties from tracking you

To stay completely anonymous and prevent the ISP and the government from spying on you, you should employ Private Internet Access VPN. It will allow you to connect to the internet while being completely anonymous by encrypting all information, prevent trackers, ads, as well as malicious content. Most importantly, you will stop the illegal surveillance activities that NSA and other governmental institutions are performing behind your back.


Recover your lost files quickly

Unforeseen circumstances can happen at any time while using the computer: it can turn off due to a power cut, a Blue Screen of Death (BSoD) can occur, or random Windows updates can the machine when you went away for a few minutes. As a result, your schoolwork, important documents, and other data might be lost. To recover lost files, you can use Data Recovery Pro – it searches through copies of files that are still available on your hard drive and retrieves them quickly.


About the author
Gabriel E. Hall
Gabriel E. Hall - Passionate computer expert

Gabriel E. Hall is an expert troubleshooter who has been working in the information technology industry for years.

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