How do I fix the “Failed to connect to the KMS server” error?

  • After installing Office on Windows 10, there is a KMS server failure problem.
  • Windows 10 prompts users to install the latest updates on their device, but sometimes the server fails to connect to the Internet.
  • There are two main reasons for this problem: The client computer does not respond to requests from the client computer.
  • The server reason: We had to do some experiments with the kms7 server recently, so we changed the default KMS port (1688) to a different one.
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Users are sometimes prompted to update their devices with Windows 10, but the server may not be able to connect to the Internet when the problem occurs. A KMS server disconnection error interrupts your work after you install MS Office on your device.

If a KMS host fails, you must install a KMS host key on a new host and then activate the host. Ensure that the new KMS host has an RR VRS in the DNS database. If you install the new KMS host with the same computer name and IP address as the failed KMS host, the new KMS host can use the failed host’s DNS SRV RR entry. If the new host has a different computer name, you can manually remove the failing host’s DNS SRV-RR or (if scanning is enabled in DNS) have DNS remove it automatically. If the network uses DDNS, the new KMS host automatically creates a new SRV RR on the DNS server. The new KMS host then begins collecting client renewal requests and begins activating clients when the KMS activation threshold is reached.

There are two main reasons why MS Office KMS server failures occur after installing on Windows 10:

  • I am unable to communicate with the client computer
  • Having trouble connecting to the Internet.

The KMS server can sometimes fail to connect after Office is installed on a Windows computer. Here are some solutions.


What causes the “Failed to connect to the KMS server” error

What causes the "Failed to connect to the KMS server" error

KMS Servers

First of all, please checkout the latest versions of my scripts here. Most people have trouble using my old ones to activate their apps. Make sure that Windows Update is enabled and your intenret connection is stable before running the batch files. 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.

The problem is primarily caused by two factors

  • The reason is the client: first of all, make sure that Windows update is enabled and that your Internet connection is stable. To check if the KMS servers are blocked or not, please open your Internet browser and try to access the page. If the page is visible, it means that this server is not blocked. Another point to pay attention to is that you must run the prompt/batch file with administrator rights. Otherwise, the connection will be interrupted by the UAC system.
  • Server reason: we had to do some experiments with the kms7 server recently, so we changed the default KMS port (1688) to a different one. We also upgraded the processor and RAM of the kms8 server. With too many daily clients, which increases over time, the server can sometimes crash. You can check on their website to see if the server is overloaded or not. To check if port 1688 is open, you can use the telnet command in Windows


How to fix the “Failed to connect to the KMS server” error

Updated: February 2024

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How to fix the "Failed to connect to the KMS server" error

Check your Internet connection

  1. You can open it by clicking the Start button.
  2. Type cmd.
  3. To open the command prompt, double-click it.
  4. By typing ping -n 25 into the command line window, you will be able to reach Google.

It is possible that the error only appears because you are having trouble connecting to the Internet. If everything appears to be working properly, you can proceed.

Update your Windows operating system

A Windows operating system that is not properly licensed often causes problems with KMS server functionality. In addition to receiving regular updates that help prevent errors, having an original license ensures that your product is legal, fully functional, and reliable.

Additionally, Windows upgrades are a one-time expense, so you will earn a return on your investment.

Make sure that your computer is activated

  1. The Control Panel is located in the KMS client.
  2. You will find a message stating that Windows is enabled.

First, make sure Windows is enabled on the client computer, then connect your Office copy to it. Once Windows is enabled, you can start adding your Office copy.

Check if you have more than 25 clients

  1. Make sure you have administrator privileges on your command prompt.
  2. In server editions, the threshold is 5; in all other versions, it is 25. To test whether the threshold has been reached, run the slmgr.VBS /dli command.

Verify that the client has contacted the host

A client computer could not communicate with the host, if there are no requests in the application event log for event ID 12290 on the host computer.

Open the right port

  1. The command line should be run as an administrator.
  2. The command slmgr.vb /dlv needs to be entered in the cmd window.
  3. Sniff the port to see if it is being sniffed.

You will find the KMS port on the host computer if you don’t know it. Any firewall rules blocking TCP traffic on the KMS port should be disabled.

Configure DNS correctly for multiple KMS hosts

  1. A domain of domain services should be set up for all computers using Active Directory.
  2. In the domain of Active Directory Domain Services, create a global security group.
  3. A global security group needs to be created for each computer running KMS.
  4. Make sure that this new group can update the DNS server by setting permissions to allow updates.

Your local network must be discovered to use KMS. When a SRV record is created on the DNS server, the first host computer will automatically announce its existence. If the DNS server is not configured properly, other hosts will not be able to modify or update the SRV record.

Newly added hosts do not increase the number of KMS

  1. The search bar should be opened on the client computer.
  2. Type cmd.
  3. Make sure Run as administrator is selected when you right-click the command line.
  4. Attempt Sysprep /generalize, or try slmgr / weapons if that doesn’t work.

Occasionally, client computers are counted together with the host and do not appear to be distinct.


RECOMMENATION: Click here for help with Windows errors.

Frequently Asked Questions

  1. Right-click the Start menu and select Command Prompt (Admin).
  2. Run the slmgr command from a script.
  3. Run the slmgr command by script.
  4. Finally, run the cscript slmgr.

Activations on the KMS server expire after 30 days, so over time the number of activations on the server drops below 25 and computers can no longer be activated.

The Key Management Service (KMS) is unavailable. This may be due to the fact that the client is configured to a specific KMS server, which may not be available. To solve this problem, you must run the "Remove KMS Saved Server" application in the CCIT Application Catalog or run the following two commands from the administrative line.

  1. Log on to the computer with an administrator account.
  2. Type cmd.exe in the search box.
  3. Right-click on cmd.exe and select "Run as administrator".
  4. Press 'Enter'.
  5. Type to complete the activation process.

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Mark Ginter is a tech blogger with a passion for all things gadgets and gizmos. A self-proclaimed "geek", Mark has been blogging about technology for over 15 years. His blog,, covers a wide range of topics including new product releases, industry news, and tips and tricks for getting the most out of your devices. If you're looking for someone who can keep you up-to-date with all the latest tech news and developments, then be sure to follow him over at Microsoft.