As you probably know, Windows 10 is free for most Windows 7 and Windows 8.1 users, but that doesn’t mean that upgrade to Windows 10 is always smooth. Users report having CMPXCHG16b / CompareExchange128 issue when upgrading to Windows 10, so let’s see how can we fix that.

How to Solve CMPXCHG16b / CompareExchange128 Problem in Windows 10

CMPXCHG16b is a special CPU instruction this is required in order to upgrade to Windows 10, and some processors lack this instruction so you won’t be able to upgrade to Windows 10.

Changing your processor is usually expensive, especially if you have older CPU that doesn’t support CMPXCHG16b instructions, so let’s see how we can fix this issue.

In the following video tutorial, we offer some helpful solutions and advice to work around this issue. Make sure to check it out and then continue with the upgrade process described just below.

Upgrade to a 64bit version of Windows 10

If you’re planning to upgrade to a 64bit version of Windows 10, you will need a processor that supports CMPXCHG16b instruction, but you can upgrade to a 32bit version of Windows 10 without any major issues. This is a workaround and not the best solution, but it’s worth giving it a try.

  1. Download 32-bit version of Windows you’re currently using and install it instead of your current version. Make sure that you create a backup for your important files.
  2. Download all the updates and when you get asked to upgrade to Windows 10, do so.
  3. You’ll upgrade to a 32bit version of Windows 10, and it will be activated on Microsoft’s servers. The great thing about this is that activation is limited only to your hardware, not to the version of Windows 10 you’re using.
  4. Download 64bit version of Windows 10.
  5. Use Creation Media program and choose to Create installation media for another PC. You’ll need an empty DVD or USB flash drive to complete this step.
  6. Perform a clean install of Windows 10 but remember to skip the step when asked to enter the serial number.
  7. Once the installation is complete, you’ll have activated and working 64bit version of Windows 10.

That’s about it, if you have any questions, comments or suggestions, just write them down in the comments, below.

Editor’s Note: This post was originally published in October 2015 and has been updated for freshness, accuracy, and comprehensiveness, including a new video tutorial for the issue.