Error 0x80005000 and DirectoryServices

I had the same again and again and nothing seemed to help.

Changing the path from ldap:// to LDAP:// did the trick.

In the context of Ektron, this issue is resolved by installing the "IIS6 Metabase compatibility" feature in Windows:

Check 'Windows features' or 'Role Services' for IIS6 Metabase compatibility, add if missing:

Ref: https://portal.ektron.com/KB/1088/

It's a permission problem.

When you run the console app, that app runs with your credentials, e.g. as "you".

The WCF service runs where? In IIS? Most likely, it runs under a separate account, which is not permissioned to query Active Directory.

You can either try to get the WCF impersonation thingie working, so that your own credentials get passed on, or you can specify a username/password on creating your DirectoryEntry:

DirectoryEntry directoryEntry = 
    new DirectoryEntry("LDAP://someserver.contoso.com/DC=contoso,DC=com", 
                       userName, password);

---

OK, so it might not be the credentials after all (that's usually the case in over 80% of the cases I see).

What about changing your code a little bit?

DirectorySearcher directorySearcher = new DirectorySearcher(directoryEntry);
directorySearcher.Filter = string.Format("(&(objectClass=user)(objectCategory=user) (sAMAccountName={0}))", username);

directorySearcher.PropertiesToLoad.Add("msRTCSIP-PrimaryUserAddress");

var result = directorySearcher.FindOne();

if(result != null)
{
   if(result.Properties["msRTCSIP-PrimaryUserAddress"] != null)
   {
      var resultValue = result.Properties["msRTCSIP-PrimaryUserAddress"][0];
   }
}

My idea is: why not tell the DirectorySearcher right off the bat what attribute you're interested in? Then you don't need to do another extra step to get the full DirectoryEntry from the search result (should be faster), and since you told the directory searcher to find that property, it's certainly going to be loaded in the search result - so unless it's null (no value set), then you should be able to retrieve it easily.

Marc