I recently installed a WSUS and set up a SUP role, however the initial Software Update sync failed.
I started the troubleshooting by checking the WSYNCMGR.log, and found the errors below :
Sync failed: WSUS update source not found on site S01. Please refer to WCM.log for configuration error details.. Source: getSiteUpdateSource
Then I checked the WCM.log and found another errors :
System.Net.WebException: The request failed with HTTP status 404: Not Found.~~ at Microsoft.UpdateServices.Administration.AdminProxy.CreateUpdateServer(Object args)~~ at Microsoft.SystemsManagementServer.WSUS.WSUSServer.ConnectToWSUSServer(String ServerName, Boolean UseSSL, Int32 PortNumber)
Remote configuration failed on WSUS Server.
The solution is to run the WSUS Configuration Wizard, go to Specify Proxy Server and click on “Start Connecting”, then close the Wizard.
Check the WSYNCMGR.log again, and we can see that the sync started working, you can also go to the console to confirm that the updates are being downloaded.