You receive an "HTTP_500" error message when you try to synchronize a mobile device with a server that is running Windows Small Business Server 2003
Article #906512
September 22, 2005
SYMPTOMS
When you try to synchronize a mobile device with a server that is running Microsoft Windows Small Business Server 2003 (Windows SBS), you receive the following error message on the mobile device:
Synchronization failed due to an error on the server. Try again. Error code: HTTP_500
CAUSE
This problem occurs if you installed Microsoft CRM on the Windows SBS server without configuring the Microsoft CRM server Web site to use a host header. When the mobile device tries to synchronize Microsoft Server Active Sync (MSAS), the synchronization request is redirected to a specific Microsoft Internet Information Services (IIS) virtual directory. This request is answered by Microsoft CRM.
http://support.microsoft.com/default.aspx?scid=kb;en-us;906512&sd=rss&spid=3208