Failed to create instance of Microsoft.SystemsManagementServer.WSUS.WSUSServer. error = The parameter is incorrect.

I was getting this error on one of the Child Primary site servers (Windows server 2008), with WSUS/SUP installed. the error was reported in wsusctrl.log

Solution: This KB article by microsoft helped:
http://support.microsoft.com/kb/962224

To resolve this issue re-register the wsusmsp.dll and the wsyncact.dll files.  To do this follow these steps:

1.       Open a CMD window and navigate to c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\.
2.       Run the following command lines in the order listed:

·         RegAsm.exe C:\Program Files\Microsoft Configuration Manager\bin\i386\wsyncact.dll /unregister
·         RegAsm.exe C:\Program Files\Microsoft Configuration Manager\bin\i386\wsyncact.dll

·         c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe C:\Program Files\Microsoft Configuration Manager\bin\i386\wsusmsp.dll /unregister
·         c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\RegAsm.exe C:\Program Files\Microsoft Configuration Manager\bin\i386\wsusmsp.dll

The above commands register the Microsoft.SystemsManagementServer.SoftwareUpdatesManagement.WSyncAction.WSyncAction  class  and the Microsoft.SystemsManagementServer.WSUS.WSUSServer class successfully.

3.       Run regedit.exe and verify that the following registry keys exist:

HKEY_CLASSES_ROOT\Microsoft.SystemsManagementServer.SoftwareUpdatesManagement.WSyncAction.WSyncAction
HKEY_CLASSES_ROOT\CLSID\{E5272449-2083-4020-ACEE-18A145F79A75}

  4.       Wait for the next Sync status to see if the sync is working now.

After reregistering, I restarted the SMS service.



Note Uninstalling and reinstalling the SUP will not resolve this issue.