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How to change the Windows XP Product Activation Key Code

Find out how to check if your Windows XP systems are using a leaked key, and how to change the product activation key if they are.

Checking the Windows XP Product Activation Key
During the installation of Windows XP Professional, you are prompted to enter a 25 digit Windows XP Product Activation Key Code, which Windows XP promptly converts it into the system's product ID. Because of security concerns about piracy, Microsoft does not provide a tool that allows you to view the Product Activation Key (or CD Key) that was used to install the operating system. However, Windows XP Service Pack 1 ships with a list of the two product IDs that are created by the pirated product volume license product keys. (The Product ID can be found by right clicking My Computer and choosing Properties.)

To determine eligibility for the update, Service Pack 1 compares the Windows XP product ID on the system to this list. The comparison and the list reside locally on the users PC and no information is sent to Microsoft as part of this process.  Service Pack 1 for Windows XP will fail to install on installations of Windows with one of the following product IDs: XXXXX-640-0000356-23XXX and XXXXX-640-2001765-23XXX

The following message will be displayed if installation fails for this reason:

Service Pack 1 Setup Error: The product key used to install Windows is invalid. Please contact your system administrator or retailer immediately to obtain a valid product key. You may also contact Microsoft Corporation's Anti-Piracy Team by emailing [email protected] if you think you have purchased pirated Microsoft software. Please be assured that any personal information you send to the Microsoft Anti-Piracy team will be kept in strict confidence.

Still on Windows XP?

If your organization has considered an OS upgrade but hasn’t pulled the trigger yet, check out this Windows 7 migration guide.

How to change your Product Activation Key in Windows XP
If the product ID matches the invalid keys above, you may need to change the key (re-enter a valid key) in order to install Windows XP service pack 1, and to make sure your environment is legal. You could completely re-install Windows XP Professional or you can try the method below. (Please backup your system before attempting this.) This workaround is only for the corporate editions of Windows XP Professional using a compromised or illegitimate key. Windows XP Home Edition and retail versions of XP Professional are not affected by Service Pack 1. Although this procedure may work with other versions of XP, we have only tested it on the corporate edition (volume license version) of Windows XP Professional.

Note: Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs.

Backup your Registry/System State

  • Backup your system state by clicking Start --> Run > and typing ntbackup -- >. Click the Advanced Mode button in the Backup Utility Wizard. Click the Backup tab, then in Click to select the check box for any drive, folder, or file that you want to back up, select the System State.
  • As an alternative, you can backup just the Registry by clicking Start --> Run --> and type in Regedit From within the Regedit screen, right click My Computer, choose Export, name the file whatever you choose, and click Save.

To change the product ID

  • Log in as the local Administrator
  • Click Start --> Run --> and type in Regedit
  • Browse to: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\wpaevents


  • In the right pane, right-click OOBETimer, and then click Modify
  • Change at least one digit of this value to deactivate Windows
  • Click OK and close regedit
  • Click Start --> Run and type in: "%systemroot%\system32\oobe\msoobe.exe /a"
  • Click "Yes, I want to telephone a customer service representative to activate Windows, and then click Next
  • Click Change Product Key (at the bottom)
  • Enter your valid Corporate Product Key
  • Press Update and close the window.
  • If you are returned to the previous window, click Remind me later
  • Restart your computer

Verify the change

  • After the workstation restarts, click Start --> Run
  • Type in: "%systemroot%\system32\oobe\msoobe.exe /a" without the quotes.
  • Make sure the dialog box says 'your copy of windows is already activated'

If you performed the above steps incorrectly, or used an invalid key, your system may not be able to boot. Use the F8 key to boot to the last known good configuration and retry with a valid key.

If you tried the above steps and nothing happens:

  • Make sure you are logged in with the local administrator account, not just an account with Administrator privileges.
  • Try replacing the %systemroot% variable with the actual drive letter that your actual directory path, especially when dual booting, or if the system path is on a drive other than C:\
  • On a normal Windows XP installation, your systemroot should be C:\windows\ so the command should be C:\Windows\system32\oobe\msoobe.exe /a
  • On systems upgraded from Windows NT/2000, the systemroot directory may be C:\Winnt\ so the command should be C:\winnt\system32\oobe\msoobe.exe /a
  • Make sure you include a space between .exe and /a in the command:
    * Correct - C:\winnt\system32\oobe\msoobe.exe /a * Incorrect - C:\winnt\system32\oobe\msoobe.exe/a
  • Product keys for XP Home Edition and retail versions of XP Professional will not activate a corporate or OEM version of XP Professional. The algorithms are different.
  • If you do not have a valid installation key for Windows XP, DO NOT e-mail us asking for a key, keygen or a crack.

Scripting the process
Microsoft has provided sample scripts for remotely updating the Product ID on multiple machines in KB Article Q328874.

You can follow on Twitter @WindowsTT.

The top 10 tips of 2005

- Introduction
- Tip #1: How to change the Windows XP Product Activation Key Code
- Tip #2: Create a bootable USB flash drive -- in a flash!
- Tip #3: Create a bootable Windows Server 2003 CD
- Tip #4: 8 common causes for 'delayed write failed' errors
- Tip #5: Ultimate boot CD packs in recovery, repair utilities
- Tip #6: Install Windows Server 2003 silently
- Tip #7: Uninstall 'stubborn' programs
- Tip #8: What to do when your hard drive fails
- Tip #9: Windows XP and Windows Server 2003 volume shadow copy service
- Tip #10: 'Unlocker' reveals processes that lock files

Bernie Klinder is a technology consultant for a number of Fortune 500 companies. He is also the founder and former editor of, a comprehensive resource index for IT professionals who support Microsoft Windows NT/2000/XP/2003 and BackOffice products. For his contributions to the information technology community, Bernie was selected as an MVP (Most Valuable Professional) by Microsoft.


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