A migration installation of SBS 2011 Standard may stop with the following error message:
The error message appears even though you have successfuly ran the Migration Preparation Tool on the Source Server.
You can press Shift F10 on the SBS 2011 Server and it will open a command prompt. The SBS setup is located at c:\program files\windows small business server\logs
Examine the log to see if it has the following highlighted errors:
4224] 110812.132120.6630: Setup: Getting OS version for SERVER  110812.132121.4580: Setup: Caught exception when getting source OS Version: System.Runtime.InteropServices.COMException (0x800706BA): The RPC server is unavailable. (Exception from HRESULT: 0x800706BA) at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo) at System.Management.ManagementScope.InitializeGuts(Object o) at System.Management.ManagementScope.Initialize() at System.Management.ManagementObjectSearcher.Initialize() at System.Management.ManagementObjectSearcher.Get() at Microsoft.WindowsServerSolutions.Setup.SBSSetup.SchemaUpdatePagePresenter.PopulateSourceServerOS(String sourceServer, String username, String password)
 110812.132125.0703: Setup: Caught exception when getting source OS Version: System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)) at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo) at System.Management.ManagementScope.InitializeGuts(Object o) at System.Management.ManagementScope.Initialize() at System.Management.ManagementObjectSearcher.Initialize() at System.Management.ManagementObjectSearcher.Get() at Microsoft.WindowsServerSolutions.Setup.SBSSetup.SchemaUpdatePagePresenter.PopulateSourceServerOS(String sourceServer, String username, String password)
The setup process makes a WMI connection to the source server to determine the source server operating system. The WMI connection attempt is failing to successfully connect. Usually there is either something misconfigured on the source server or something blocking the WMI connection.
You can use the following steps to help troublehsoot the issue.
1. Verify that DCOM is properly configured on the source server.
a. On the source server, run dcomcnfg . Expand component servicesc. Expand Computers d. Right click on My Computer and go to properties e. Verify that the settings on the Default Properties tab match those in the following screenshot:
2. Verify that WMI is working on the source server.
a. On the source server, run WBEMTEST
b. Click connect
c. Change the namespace to root\cimv2
d. If it fails to connect you will receive an error popup dialog. If you get an error in the connection you should examine the application event log on the source server and look for WMI related events that can aid in troubleshooting the failure.
3. If WMI connects locally then we need to test remote connectvity to WMI.You can press shift F10 on the SBS 2011 and a command prompt should open. You can use WBEMTEST to test WMI connectivity from the new server to the source server.
d. In the User Field enter the account name you specified in the SBS Answer File
e. Enter the password for the account in the password Field
f. Press the Connect button
g. If it fails to connect, typically you will receive one of two errors:
If you get either error message, then we need to examine the source server and disable any firewall, antivirus, antispyware programs or anything that could interfere with RPC network connections from the SBS 2011 Server. The first steps would be to use msconfig and disable any start up items and any third party services and then reboot the SBS 2003 Server. After the reboot, use wbemtest on the SBS 2011 server or hit the check again option on the error message to see if the issue is resolved. If you are still getting a failure, there may be a permission problem on the SBS 2003 server. Since the SBS 2003 server is going to be decommissioned once the migration is complete, you can change the startup account for the RPC service on the SBS 2003 server to local system. We do not recommend permanently changing the RPC service logon account on a server that is going to remain in production. If the source server is not SBS 2003, you can temporally change the RPC service to run under the Local System account. Once the SBS 2011 server is completely installed, you can change the service back to network service. If the RPC service runs under the context of the local system account, it can often bypass any security problems on the SBS 2003 server. Use the following steps to change the RPC server to run under the local system account:
a. On the SBS 2003 server open the Services MMC
b. Open the properties of the service named Remote Procedure Call (RPC)
c. Click on the Log On Tab:
d. Change the Log on account to Local System Account and check the box to allow the service to interact with the desktop.
e. Reboot the SBS 2003 Server
f. Once the SBS 2003 Server reboots, click on the check again box to recheck the connection.