ConfigMgr 2007 R2 SP2: Windows Server 2008 R2, WSUS 3.0 SP2 on Site Server

And we have another one!

In my testlab I have WSUS setup on the same server as the SCCM Site Server. However, when trying to setup the Active SUP I got the following error in the WSYNCMGR.log

SMS WSUS Synchronization failed. Message: WSUS server not configured. Source: CWSyncMgr::DoSync. The operating system reported error 2147500037: Unspecified error

From this message it looks as if WSUS could not be contacted, but the WSUSCtrl.log states that all connections to the WSUS server are succesful. After searching around it seemed that this issue was due to the fact of WSUS and the SCCM Site Server being on the same machine. The fix is as follows (also check out http://support.microsoft.com/kb/896861 for more information (choose Method 1)):

1) Fire up regedit.
2) Go to HKLM\System\CurrentControlSet\Control\LSA
3) Create a new DWORD value called DisableLoopbackCheck
4) Edit the value and in the Value Data box type 1
5) Close regedit
6) In the SCCM Console right-click on Update Repository and check the WSYNCMgr.log for any issues.

In my case this fixed my issues.