About Genuine Windows

Support for Windows 7 ended on January 14, 2020

We recommend you move to a Windows 10 PC to continue to receive security updates from Microsoft.

Genuine versions of Windows are published by Microsoft, properly licensed, and supported by Microsoft or a trusted partner. You’ll need a genuine version of Windows to access the optional updates and downloads that help you get the most from your PC.

To learn how to activate Windows, see Activate Windows 7 or Windows 8.1. If you’re using Windows 10, see Activation in Windows 10.

Here are answers to some common questions about genuine Windows software.

Look for key features of genuine Windows software, such as the Certificate of Authenticity (COA), a proof of license label, and an edge-to-edge hologram. For more information, visit the What to look for page on the Microsoft How to Tell website. Your safest option is always to buy Windows from Microsoft, or to buy a PC with Windows preinstalled directly from Microsoft or a store you know and trust.

If you’re seeing these notifications, it’s likely that your copy of Windows wasn’t properly activated. Click the notification and follow the steps to repair Windows or buy a genuine version of Windows if you find out the software is counterfeit.

Until you correct the issue, you’ll receive periodic reminders that Windows is not genuine. Your desktop may also turn black to emphasize the messages. You can reset it, but it will return to black every 60 minutes until the issue is resolved.

Windows will always be able to get critical security updates, even if your version isn’t genuine. However, other updates and benefits are available exclusively for genuine Windows software.

Activation helps verify that your copy of Windows is used only on PCs that the Microsoft Software License Terms allow. It pairs your product key or digital entitlement with your hardware configuration. Usually, you only need to activate Windows once, unless you make a significant hardware change.

When your PC downloads updates, Windows checks to see if your product key or digital entitlement is valid. If it is, you’re eligible to receive the latest updates from Microsoft. If it’s not, your PC is running non-genuine Windows.

You can’t install Windows on more PCs than the Microsoft Software License Terms allow. Usually, a copy of Windows can only be installed on one PC. To learn more about licensing Windows on more than one PC, go to the Microsoft Volume Licensing website.

Yes. You’ll still be able to get critical security updates. However, many updates are exclusively for customers with genuine versions of Windows. We strongly recommend that you get genuine Microsoft software immediately to keep you safer while using your PC.

Validation is an online process. It verifies that your copy of Windows is genuine and that critical Windows licensing files haven’t been damaged, deleted, or removed. It takes only a few moments and lets Microsoft create a match between your PC’s hardware profile and your 25-character product key or digital entitlement.

Your copy of Windows may need to be validated before you can get downloads and the updates which are reserved for PCs that are running genuine Windows. Windows might also prompt you to run genuine validation if activation isn’t properly completed.

If your copy of Windows fails validation, you’ll see a results page that tells you why it isn’t genuine. You’ll also see info about how to resolve the issue.

There are a few common scenarios in which Windows running on a PC might be discovered to be non-genuine during validation.

Repairs. If your PC has been repaired, you might start to see messages on your desktop that Windows isn’t genuine. If the repairs required Windows to be reinstalled, the technician may have activated Windows with a different key than you used when it was originally installed. You might not see the messages until you try to download something from the Microsoft Download Center that requires validation, and validation fails. To fix the issue, you can properly activate Windows by reentering your original product key.

For other issues, you may need to buy a genuine version of Windows.

1 License = 1 PC. Another common cause of Windows validation failure happens when you try to install Windows on more PCs than your license allows. For instance, if you purchased a copy of Windows and installed it on more than one PC, online validation might fail because the product key has already been used on another PC. The rule for most copies of Windows is that only one copy of Windows can be installed on one PC. To learn about licensing more than one PC, go to the Microsoft Volume Licensing website.

Counterfeit software. Validation will also fail if you’ve inadvertently acquired and installed counterfeit Windows software. The Microsoft How to Tell website can help you identify counterfeit software and file a counterfeit software report if needed. Validation failure is common for versions of Windows that were purchased from an online auction site, or if Windows was on a used PC that you purchased. Remember to ask the seller for the Certificate of Authenticity and the original Windows disc, if there was one.

To file a counterfeit report, go to the Microsoft How to Tell website.

You can file an online report if you inadvertently bought or received counterfeit software, or have information about a person, business, or online site that might be selling counterfeit software. The report you submit will be treated as confidential. Microsoft devotes substantial time and energy to fighting software counterfeiting, and you can be assured that we will take appropriate action in response to your report.

If you got an error when you were activating Windows, you can find what it means. For details, go to Get help with activation errors.

You’ll need a product key when you install Windows. To learn more, go to Find a product key.

Fix problems that block programs from being installed or removed

Note: Use these steps for Windows programs. If you’re having problems with an app you got from Microsoft Store, go to Fix problems with apps from Microsoft Store.

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you’re blocked from installing or removing programs. It also fixes corrupted registry keys.

First, you’ll need to download the troubleshooter.

If you see the File Download box when you start downloading, select Run or Open.

The troubleshooter provides steps for you to follow. If a program isn’t listed in the uninstall options, you’ll be asked for that program’s product code. To access the code, you’ll need a tool for reading MSI files—which is typically available to IT professionals. You’ll find the product code in the property table of the MSI file.

What it fixes

The troubleshooter helps fix problems that:

Corrupt registry keys on 64-bit operating systems.

Corrupt registry keys that control the update data.

Prevent new programs from being installed.

Prevent existing programs from being completely uninstalled or updated.

Block you from uninstalling a program through Add or Remove Programs (or Programs and Features) in Control Panel.

If you’re trying to remove malware, you can use Windows Security (or another antivirus tool), or you can use the Windows Malicious Software Removal tool.

Get help with Windows 10 upgrade and installation errors

There are many reasons why you might receive an error message when upgrading or installing Windows 10, but common errors can be fixed with a few steps that you can do on your own. Note: An upgrade takes your device from an older version of Windows, such as Windows 7 or Windows 8.1, to Windows 10.

Before searching for a specific error code, try the tips listed in General fixes. If those don’t fix your upgrade or installation problem, check the table of error codes at the bottom of this article.

General fixes

Here are some things you can try to fix upgrade and installation errors:

Unplug any nonessential hardware devices. These could include headphones, printers, scanners speakers, USB flash drives, and external hard drives.

If you’re using a laptop and it’s plugged in to a docking station, undock it.

It’s a good idea to make sure that all important updates are installed before trying to upgrade Windows. This includes updates to hardware drivers on your device.

For information and to make sure you’re up-to-date, see Windows Update: FAQ.

Use Windows Defender to protect your device during the upgrade—non-Microsoft antivirus software can sometimes cause upgrade problems. As long as you have installation media and all required activation information, you can always reinstall the software after you upgrade.

To remove an antivirus application, go to Control Panel\Programs\Programs and Features. Select the program, and then select Uninstall. Select Yes to confirm.

Outdated software can cause problems with a Windows upgrade, so removing old or nonessential applications can help.

If you plan to reinstall the application later, make sure you have the installation media and all required activation information before removing it.

To uninstall software, go to Control Panel\Programs\Programs and Features. Select the program, and then select Uninstall. Select Yes to confirm.

To upgrade to Windows 10, you need enough space on your hard drive for the installation to take place.

To view how much hard drive space is available on your computer, select the Start button, then in the search box on the taskbar, type File Explorer (known as Windows Explorer in Windows 7).

Then select Computer or This PC and look under Hard Disk Drives or under Devices and drives. If there are multiple drives listed, the system drive is the drive that includes a Microsoft Windows logo above the drive icon. You’ll see the amount of available space under the drive.

If it looks like your drive is running low on space, see Tips to free up drive space on your PC.

0xC1900101 Errors

An error that begins with 0xC1900101 is usually a driver error. If you see any of these error codes, try the following steps first to fix the problem. If these steps don’t work, see Resolve Windows 10 upgrade errors for more detailed technical info.

Make sure that your device has enough space. Your device requires at least 16 GB of free space to upgrade a 32-bit OS, or 20 GB for a 64-bit OS. For more info, see Free up drive space in Windows 10.

Run Windows Update a few times. Download and install any available updates in Windows Update, including software updates, hardware updates, and some third-party drivers. Use the troubleshooter for Windows 10 to fix Windows Update errors.

Check third-party drivers and download any updates. You can find third-party drivers and installation instructions for any hardware you’ve added to your device on the manufacturer’s website.

Unplug extra hardware. Remove all external storage devices and drives, docks, and other hardware you might have plugged into your device that isn’t needed for basic functionality.

Check Device Manager for errors. Select the Start button, then in the search box on the taskbar, type device manager. Choose Device Manager from the results. In the window that pops up, look for any device with a yellow exclamation mark beside it (you may have to select each category to switch to the list of devices). Press and hold (or right-click) the device name and select either Update Driver Software or Uninstall to correct the errors.

Remove third-party security software. Make sure you know how to reinstall your programs and that any necessary product keys are on hand. Windows Defender will help protect your device in the meantime.

Repair hard-drive errors. Select the Start button, then in the search box on the taskbar, type command prompt. Choose Command Prompt from the list of results. In the window that pops up, type chkdsk/f C: and press the Enter key. Repairs automatically start on your hard drive, and you’ll be asked to restart your device.

Note: You must have administrator permissions on your device to do this.

Do a clean restart into Windows. Learn how.

Restore and repair system files. Select the Start button, then in the search box on the taskbar, type command prompt. Choose Command Prompt from the list of results. In the window that pops up, type DISM.exe /Online /Cleanup-image /Restorehealth and press the Enter key. (Learn to repair a Windows image)

Note: You must have administrator permissions on your device to do this.

Other Common Errors

The following table lists the most common upgrade and installation errors and some things you can try to fix them. If you continue having problems upgrading or installing Windows 10, contact Microsoft support.

What it means and how to fix it

This indicates that there was a problem downloading and installing the selected update. Windows Update will try again later and there is nothing you need to do at this time.

This could indicate that an incompatible app installed on your PC is blocking the upgrade process from completing. Check to make sure that any incompatible apps are uninstalled and then try upgrading again.

A cleanup operation from a previous installation attempt is still pending, and a system restart is required to continue the upgrade. Restart the device and run setup again. If restarting device does not resolve the issue, then use the Disk Cleanup utility and clean up the temporary files and the System files. For more information, see Disk cleanup in Windows 10.

A file needed by Windows Update is likely damaged or missing. Try repairing your system files: Select the Start button and type command prompt in the search box on the taskbar. Choose Command Prompt from the list of results. In the window that appears, type DISM.exe /Online /Cleanup-image /Restorehealth and press the Enter key.

This may signify that your PC doesn’t meet the minimum requirements to download or install the upgrade to Windows 10. Learn more about the minimum requirements for Windows 10

This might indicate that a driver or other software on your PC isn’t compatible with the upgrade to Windows 10. For info about how to fix this problem, contact Microsoft support.

This could mean that the upgrade process was interrupted because you accidentally restarted your PC or signed out of your PC. Try upgrading again and make sure your PC is plugged in and stays turned on.

This error might mean that your PC couldn’t connect to the Windows Update servers. If you’re using a VPN connection to connect to a work network, disconnect from the network and turn off the VPN software (if applicable) and try upgrading again.

The error could also mean there isn’t enough free space in the System Reserved partition. You might be able to fix this problem by using third-party software to increase the size of the System Reserved partition.

Error: We couldn’t complete the updates. Undoing changes. Don’t turn off your computer.

Error: Failure configuring Windows Updates. Reverting changes.

These are generic errors that might appear any time a Windows update fails. You’ll need to determine the specific error code to investigate how to best resolve this problem.

You can find the error code for the failed update by viewing your update history. Look for the update that wasn’t installed, note the error code, and then contact Microsoft support.

To view your update history in Windows 8.1:

Open Windows Update by swiping in from the right edge of the screen (or, if you’re using a mouse, pointing to the lower-right corner of the screen and moving the mouse pointer up), select Settings > Change PC settings > Update and recovery > View your update history.

To view your update history in Windows 7:

Select the Start button. In the search box, type Update, and then, in the list of results, Select Windows Update > View update history.

Error: The update isn’t applicable to your computer.

This error might mean that your PC doesn’t have the required updates installed.

Check to make sure that all important updates are installed on your PC before you try upgrading.

This likely indicates that your PC doesn’t have enough space available to install the upgrade.

Free some space on the drive and try again. Get tips for freeing up drive space

The specified disk operation is not supported by the target disk, partition, or volume.

Make sure your machine meets the minimum requirements to install Windows 10.

The system cannot find the file specified.

If you have a disk or disks where you are not installing Windows 10 on, remove those disks.

A driver has caused a problem.

Disable or remove all 3rd party antivirus or antispyware from your system. Disconnect all peripheral devices that are connected to the system, except for the mouse, keyboard and display.

Contact your hardware vendor to obtain updated device drivers.

Windows Setup terminated unexpectedly due to another process running in the background.

When you start Windows by using a normal startup, several applications and services start automatically, and then run in the background. These programs include basic system processes, antivirus software, system utility applications, and other software that has been previously installed. These applications and services can cause interference when you attempt to upgrade to the latest version of Windows 10.

To help you determine whether a background program is interfering with the upgrade, a «clean boot» may be needed. See How to perform a clean boot in Windows.​

Windows Setup terminated unexpectedly due to another process running in the background.

Uninstall any antivirus or antispyware software and update again.