Request IP Address has different address family from network address.

Published on 12 March 2008 • Estimated reading time: 1 minutes

Here is a new great error for Microsoft Dynamics CRM 4.0: "Request IP Address has different address family from network address." You may encounter this when opening MSCRM or in the event log. If you see it in the event log, it means that workflows don’t work, imports never happen, emails don’t flow, and Outlook clients cannot connect. Lastly, it is likely you are using Windows Server 2008 (though I suspect this can also affect Windows Server 2003).

The issue is that MSCRM 4.0 doesn’t support IPv6 (as explained in Microsoft KB 950100), but server names are resolving internally to IPv6 addresses. The easiest way to test is to ping the server name and localhost—if you get an IPv6 address, you’re in trouble.

The fix is simple:

1. Open your hosts file (<system drive>:\windows\system32\drivers\etc\hosts).
2. Add a line for your server name with an IPv4 address.
3. Save the file and ping again to confirm it works.
4. Once confirmed, run an IISReset—and you’re done!