When creating a cluster using System Center 2012 Virtual Machine Manager (VMM), the creation process fails and the following error is generated:
Error 25310 Unable to connect to the user host process
Running a Cluster Validation Report on the Hyper-V hosts only generates warnings. Reviewing a VMM trace may show events such as the following:
 0E30.1250::02/28-17:51:51.498#19:RunningTaskDbWriter.cs(771): UpdateRunningStepDescription --> SubtaskID: f0e3931f-22d5-4c4d-a693-dfec95b5a51e, Description Validate nodes for clustering|TaskID=931E55C6-E62D-4938-9A10-AB556F879ACA  0E30.1250::02/28-17:51:51.502#09:InstallClusterSubtask.cs(392): The cluster operation failed before cluster creation. cleaning up cluster in DB  0E30.1250::02/28-17:51:51.505#09:InstallClusterSubtask.cs(392): Microsoft.VirtualManager.Utils.CarmineException: Unable to connect to the user host process.  retry the operation.  at Microsoft.VirtualManager.VmmHelperHost.HostHelper`2.ConnectToProcess(TimeSpan& timeout, String namedPipeName)  at Microsoft.VirtualManager.VmmHelperHost.HostHelper`2.CreateProcess(TimeSpan timeout)  at Microsoft.VirtualManager.VmmHelperHost.HostHelper`2.CreateProcess()  at Microsoft.VirtualManager.Engine.Adhc.TestClusterSubtask.RunSubtask()  at Microsoft.VirtualManager.Engine.TaskRepository.SubtaskBase.Run()  at Microsoft.VirtualManager.Engine.Adhc.InstallClusterSubtask.RunClusterValidationOnHosts()  at Microsoft.VirtualManager.Engine.Adhc.InstallClusterSubtask.RunSubtask()  *** Carmine error was: UserHostConnectFailed (25310)
This has been seen to occur in the following scenarios:
If there is no default gateway on any of the Network Interface Adapters (NICs) on the Hyper-V hosts that are being clustered.
If VMM services times out attempting to connect to the VmmHelperHost process
To resolve this issue, ensure a default gateway is defined on one of the cluster NICs on each node that have a compliant status in VMM on the Hyper-V hosts.
If the problem is not resolved, consider increasing the HelperHostConnectRetryCount from the default of 5 to a larger value such as 10. This will effectively increase the timeout from 10 seconds to 50 seconds.
Warning: Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
For Windows Server 2008 R2 Click Start, and in the Search box type regedit, and then clickregedit.exe in the search results.
1. Locate, and then click the following subkey:
HKLM\Software\Microsoft\ Microsoft System Center Virtual Machine Manager Server\Settings
2. Click on Edit, and then New - DWORD Value.
3. Rename the value to HelperHostConnectRetryCount
4. Right click on HelperHostConnectRetryCount and then click Modify.
5. In the Edit DWORD Value dialog box, type 10in the Value databox, select Base of Decimal and then click OK.
6. Quit Registry Editor