An unexpected error occurred. (Fault Detail is equal to Microsoft.Xrm.Sdk.OrganizationServiceFault).

In my previous post, I described how to import a solution programmatically, one thing I did not do was show how I instantiated the OrganizationServiceProxy nor how I had configured the Application Pools for the MS Dynamics website.

This is the method I used to instantiate the OrganizationServiceProxy:

 private OrganizationServiceProxy InstantiateOrgService(OrganizationServiceProxy service, string OrgName, string FQDN, int port = 80, int TimeOut = 600)
 {
     try
     {
         ClientCredentials creds = new ClientCredentials();
         creds.Windows.ClientCredential = (NetworkCredential)CredentialCache.DefaultCredentials;
 
         service = new OrganizationServiceProxy(new Uri(string.Format(Constants.OrgURL, FQDN, port, OrgName)), null, creds, null);
         service.Timeout = new TimeSpan(0, 0, TimeOut);
 
         return service;
     }
     catch (Exception ex)
     {
         MessageBox.Show(string.Format("Unable to instatiate the Org Service. Exception {0}", ex));
 
         return null;
     }
 }

I had another method that I had used where I passed in an specific set of credentials, rather than using default credentials, and that method had worked fine, but when I changed to the method above, it would not work and I would get this rather helpful message:

An unexpected error occurred.
(Fault Detail is equal to Microsoft.Xrm.Sdk.OrganizationServiceFault).

After a lot of hair pulling and useless Google searches (sorry my esteemed friend) I realized what I had changed, I was using Default Credentials, but the Application pool was not configured to use a domain account, so I changed the account running the CRM Application Pool to a domain account and this resolved the issue: