PowerShell Remoting [CredSSP]: HTTP 500 from WinRM Service

I started getting HTTP 500 messages from the Windows Remote Management (WinRM) service on all of my test Windows Server 2012 systems, butonly when trying to use CredSSP (Credential Security Support Provider) to authenticate to the remote system. I can successfully establish a standard, Kerberos remote session, and I can also successfully establish SSL connections to them, using the -UseSSL switch parameter on the Enter-PSSession cmdlet.

The error message I'm getting, when I try to run:

$Cred = Get-Credential;
Enter-PSSession -ComputerName server01.contoso.com -Authentication CredSSP -Credential $Cred;

Is this:

Enter-PSSession : Connecting to remote server server01.contoso.com failed with the following error message : The WinRM
client received an HTTP server error status (500), but the remote service did not include any other information about
the cause of the failure. For more information, see the about_Remote_Troubleshooting Help topic.
At line:1 char:1+ Enter-PSSession -ComputerName server01.contoso.com -Authentication Credssp -Creden ...+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : InvalidArgument: (server01.contoso.com:String) [Enter-PSSession], PSRemotingTransportExcep
   tion+ FullyQualifiedErrorId : CreateRemoteRunspaceFailed

So far, I have tried:

1. Disabling all GPOs related to credential delegation, WinRM configuration, and PowerShell
2. Disable-PSRemoting -Force;
3. Disable-WSManCredSSP -Role Client;
4. Disable-WSManCredSSP -Role Server;
5. Enable-PSRemoting -Force;
6. Set-WsmanQuickConfig -UseSSL;
7. On client: Enable-WsmanCredSSP -Role Client -DelegateComputer *.contoso.com;
8. On remote system: Enable-WsmanCredSSP -Role Server;

On the client system, in the Windows Remote Management event log, I'm seeing this message: WSMan operation CreateShell failed, error code 2150859120

In this scenario, both the client and server are running Windows Server 2012, withPowerShell v3.0.

Any thoughts on this error?

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