FIX for product key failure 0800402c9 RRS feed

  • Question

  • Key Update Tool 6.0.3790.0 (latest as of this date) will not run on XP Servie Pack 3 (SP3).  It erroneously gives the error message disk-write error 0800402c9.  This is a bug in the Key Update Tool.



    1. Restore back to level SP2

    2. Run the KeyUpdateTool.exe

        It will now allow you to enter the new Product Key you  have purchased.

    3. Re-install SP3 - preferably by using Windows Update.

        Be sure to run Windows Update at least 3 times to get all fixes applied.


    This circumvention has been tested and works.


    Perhaps Microsoft will acknowledge this bug at some time in the future and fix the Key Update Tool so that you can run it at level XP SP3.  In the meantime ignore support's guesses leading you down the primrose path and use this circumvention.



    Tuesday, May 13, 2008 11:15 PM


All replies

  • rgp1842,


    The Key Update Tool has been updated and can be found here:




    Lori MS



    Thursday, May 15, 2008 11:41 PM
  • I don't have the ability to test this fix.  I circumvented the problem as described, and no longer have the need to use the Key Update Tool.  Perhaps one of the other forum members can test it.  It's a day late and a dollar short for me, but thanks for the bug fix anyway for those who will surely need it (which appear to be many based on all the postings here on this subject).




    Saturday, May 17, 2008 1:43 AM
  • Hi Lori MS,

    Just like to say I had tested the update tool. It works. Thanks for the link!

    • Edited by FanFan82 Friday, August 8, 2008 11:04 AM insufficient info
    Friday, August 8, 2008 11:03 AM