How to fix "The WinRM client cannot process the request. Kerberos authentication cannot be used with implicit credentials if the client computer is not joined to a domain."

Error Description

This error occurs when you attempt to use Windows Remote Management (WinRM) to connect to a remote computer using Kerberos authentication, but your local computer is operating in a Workgroup rather than being joined to an Active Directory domain. Kerberos strictly requires a centralized domain infrastructure to validate credentials. When you do not explicitly provide user credentials (implicit credentials), WinRM defaults to Kerberos and expects your local machine identity to be part of that domain, which fails in a Workgroup environment.

Step-by-Step Fixes

To resolve this issue, you must either configure WinRM to trust the remote host using NTLM authentication or explicitly provide credentials during the connection.

Method 1: Add the Remote Host to the TrustedHosts List

Since Kerberos cannot be used, you must tell your local computer to trust the remote machine using NTLM authentication.

1. On your local computer, click the Start menu, type PowerShell, right-click it, and select Run as administrator.
2. Run the following command to check your current TrustedHosts configuration:

   Get-Item WSMan:\localhost\Client\TrustedHosts

3. Run the following command to allow your computer to connect to the specific remote IP address or hostname (replace REMOTE COMPUTER IP OR NAME with your actual remote machine's details):

   Set-Item WSMan:\localhost\Client\TrustedHosts -Value "REMOTE COMPUTER IP OR NAME" -Force

   Note: If you want to connect to any computer (less secure, recommended only for private networks), you can use a wildcard symbol `""` instead.*

4. Restart the WinRM service to apply the changes by running:

   Restart-Service WinRM

Method 2: Pass Explicit Credentials and Define Authentication Type

When executing your WinRM or PowerShell Remoting commands, you must explicitly supply a username and password instead of relying on implicit credentials, and specify the authentication mechanism.

If you are using PowerShell Remoting (Enter-PSSession or Invoke-Command):

1. Open PowerShell.
2. Use the -Credential parameter alongside the -Authentication parameter set to Negotiate or Basic.
3. Run the connection command like this:

   Enter-PSSession -ComputerName REMOTE COMPUTER IP OR NAME -Credential (Get-Credential) -Authentication Negotiate

4. A pop-up window will appear. Enter the username and password of an administrator account that exists on the remote computer.

Method 3: Verify WinRM Authentication Settings on Both Computers

Ensure that the WinRM client and server are configured to allow NTLM (Negotiate) authentication.

1. Open PowerShell as an administrator on both the local and remote computers.
2. Run the following command to view the enabled authentication types:

   Get-ChildItem WSMan:\localhost\Service\Auth
   Get-ChildItem WSMan:\localhost\Client\Auth

3. Ensure that Negotiate and Basic (if needed) are set to True. If Negotiate is set to False, enable it by running:

   Set-Item WSMan:\localhost\Client\Auth\Negotiate -Value \$true
   Set-Item WSMan:\localhost\Service\Auth\Negotiate -Value \$true