LDAP The server is not operational error occurs on Windows 10 Only

Question

I has been using this function to find the users email address from their username (all my users are on the same domain) without problems, but now some of the users have been upgraded to Windows 10 and I'm getting an error:

The server is not operational

I have made changes to my code with reference to this question and the answer, so now I pick up the default naming context, but the error persists: System.DirectoryServices - The server is not operational

    Public Function UserEmail(ByRef Username As String) As String
        UserEmail = ""
        Dim deRoot As New DirectoryServices.DirectoryEntry("LDAP://RootDSE")

        If Not deRoot Is DBNull.Value Then
            Dim defaultNamingContext As String = deRoot.Properties("defaultNamingContext").Value.ToString()
            Dim path As String
            path = "LDAP://" & defaultNamingContext


            Dim entry As New DirectoryServices.DirectoryEntry(Path)
            Dim search As New DirectoryServices.DirectorySearcher(entry)

            search.Filter = "(&(objectClass=user)(anr=" + Username + "))"
            search.PropertiesToLoad.Add("mail")

            Dim result As DirectoryServices.SearchResult
            result = search.FindOne

            If IsDBNull(result) Then
                UserEmail = ""
            Else
                UserEmail = result.Properties("mail")(0)
            End If

        End If

    Return UserEmail
End Function

The code works fine where my users are using Windows 7 and 8.

Any suggestions?

yes, it works fine in Windows 7 and 8 but errors out in Windows 10. It sends email to another user where that username has been saved in a database. — DovesandChicks, May 17 '16 at 16:05
Are those Windows 10 machines joined to the same domain as the Windows 7/8 ones? — Gabriel Luci, May 17 '16 at 19:30
They are all on the same domain, and the line dim deRoot as New DirectoryServices throws an exception. — DovesandChicks, May 19 '16 at 06:54
The error has stopped happening without my intervention, I think there have been some changes made to the firewall and router. — DovesandChicks, Jul 25 '16 at 12:13

score 0 · Answer 1 · answered May 19 '16 at 12:19

I don't know why it would be crashing at LDAP://RootDSE. But If you only have one domain, you could hard code the domain name rather than using RootDSE.

You can use either the domain DNS name:

Dim entry As New DirectoryServices.DirectoryEntry("LDAP://domain.com")

Or the domain distinguished name:

Dim entry As New DirectoryServices.DirectoryEntry("LDAP://DC=domain,DC=com")

See if that makes any difference.

LDAP The server is not operational error occurs on Windows 10 Only

1 Answers1