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Windows KMS Activation Lost

KMS licensing is great.  It makes deployment and license management extremely easy for IT, however every now and then something “goes wrong” and the system loses its activation status.

Luckily, Microsoft has a script called slmgr.vbs that is used to register and re-register Windows.  More information on slmgr.vbs can be found at

In order to re-correct this behavior and get the system talking to your KMS server again, you have a few options.

  1. Disjoin the system and re-join it to the domain.
  2. Reimage the system (not exactly a time saver here)
  3. Use slmgr.vbs to re-activate Windows.  (Note: slmgr.vbs can also be used to convert MAK licenses into KMS)

Today, we’ll be covering the third method of using slmgr.vbs to re-activate a Windows Vista and above client.  First off, we’ll need to drop to a command prompt and change directories over to C:\Windows\System32

In this directory you will find the slmgr.vbs script.  You can view all of the slmgr.vbs options at

For this example, we simply have a KMS client who is no longer talking to the KMS server and has lost its activation status.  For this, we will use the following command: slmgr.vbs /ipk <Product_Key>

Now you may be wondering where we find the Product Key at.  Luckily for us, Microsoft uses the same KMS License Key for KMS Activation (NOTE: You do have to have a KMS Server up and running for this to work).  You can find those Product Keys here:

After finding the right key, simply insert it into the command string above and your system should be talking to your KMS Licensing Server again.  You may want to reboot the system for good measure here also.

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