Troubleshoot “connection to KMS server failed” error

Posted by in Computer Tips | Last updated on

I have received a lot of complaint emails saying that they could not activate their program after folowing instructions in my videos. The issues described here are related to an error message they got as below.

The connection to my KMS server failed! Trying to connect to another one… Please wait…
Sorry! Your version is not supported.

There are two main causes of this issue.

1. The cause of client

First of all, please make sure that Windows Update is enabled and your intenret connection is stable. To check if my KMS servers are blocked or not, please open your internet browser then try going to: If the page is visible, it means this server is not blocked.
One other point to note is that you need to run command prompt/batch file with admin rights.

Make sure "administrator" is in the title
Make sure “administrator” is in the title

Otherwise, the connection will be denied by UAC system.

2. The cause of server

Recently I need to do some experiments in the kms7 server so I changed the default KMS port (1688) to another one. And besides, I upgraded CPU and RAM memory on the kms8 server.
Because the number of daily clients is too big and still increasing over time, so the server can also be stuck at times. You can check and see if the server is overloaded or not here:

To check if the port 1688 is open, you can use the telnet command on windows or use this online port check tool in simpler way.

If you would have any questions or concerns, please leave your comments. I would be glad to explain in more details. Thank you so much for all your feedback and support!

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212 thoughts on “Troubleshoot “connection to KMS server failed” error

    1. YEAH!

      remove the port and just use “”

      like this

      elevatated command propmpt/Powershell command:
      define the KMS Server :
      cscript slmgr.vbs -skms
      then run
      cscript slmgr.vbs /ato
      works fine just did it.