Unspecified error thrown on deployment system, when creating Outlook object

Question

I have an application which integrates with Outlook, just to send an email with attachments (VB.NET .net v4).

Because I need it to run with multiple versions of Outlook, I am using late binding.

On my local system, and another deployment system, everything works fine (Outlook 2016).

On 3 particular systems, I can't create the "Outlook.Application" object, because an exception is thrown and, unfortunately, the error tells me nothing. This just happens if Outlook is running. (All systems running win 10)

I am running the application from a network share, however I already tried to run locally from c: drive and documents directory. Also tried running as administrator.

Another thing I have tried, was to check if Outlook is running to get the object, instead of creating, but the error remains if Outlook is running.

This is what I am using:

Public Class Email

    Public Shared Sub EnviaEmail(ByVal pEnderecoDestino() As String, ByVal pAssunto As String, ByVal pBody As String, Optional ByVal pEnderecoCC() As String = Nothing, Optional ByVal pEnderecoBCC() As String = Nothing, Optional ByVal pAnexos() As String = Nothing)

        Dim objOutlook As Object
        Dim objMensagem As Object
        Dim objEnderecos As Object
        Dim objEndereco As Object
        Dim objAnexos As Object

        Try
            Dim fechaApp As Boolean = False

            If Process.GetProcessesByName("OUTLOOK") Is Nothing Then fechaApp = True

            objOutlook = CreateObject("Outlook.Application")          

            objMensagem = objOutlook.CreateItem(0)

            With objMensagem
                .Subject = pAssunto
                .BodyFormat = 1
                .Body = pBody
            End With

            objEnderecos = objMensagem.Recipients

            For i As Integer = 0 To pEnderecoDestino.Length - 1 Step 1
                If Not String.IsNullOrEmpty(pEnderecoDestino(i)) Then
                    objEndereco = objEnderecos.Add(pEnderecoDestino(i).Trim())
                    objEndereco.Type = 1
                    objEndereco.Resolve()
                End If
            Next i

            If Not pEnderecoBCC Is Nothing Then
                For i As Integer = 0 To pEnderecoBCC.Length - 1 Step 1
                    If Not String.IsNullOrEmpty(pEnderecoBCC(i)) Then
                        objEndereco = objEnderecos.Add(pEnderecoBCC(i).Trim())
                        objEndereco.Type = 3
                        objEndereco.Resolve()
                    End If
                Next i
            End If

            If pEnderecoCC IsNot Nothing Then
                For i As Integer = 0 To pEnderecoCC.Length - 1 Step 1
                    If Not String.IsNullOrEmpty(pEnderecoCC(i)) Then
                        objEndereco = objEnderecos.Add(pEnderecoCC(i).Trim())
                        objEndereco.Type = 2
                        objEndereco.Resolve()
                    End If
                Next i
            End If

            objAnexos = objMensagem.Attachments

            If pAnexos IsNot Nothing Then
                For i As Integer = 0 To pAnexos.Length - 1 Step 1
                    objAnexos.Add(pAnexos(i))
                Next i

            End If


            objMensagem.Send()


            If fechaApp Then objOutlook.Quit()

        Catch ex As COMException

            Select Case ex.ErrorCode

                Case -2147467260
                    Throw New Exception("Permission denied to access MS Outlook", ex.InnerException)

                Case -2147221164
                    Throw New Exception("MS Outlook not installed" , ex.InnerException)

                Case Else
                    Throw ex
            End Select

        Finally
            objAnexos = Nothing
            objEndereco = Nothing
            objEnderecos = Nothing
            objMensagem = Nothing
            objOutlook = Nothing
        End Try
    End Sub

End Class

Answer 1

The fact you only see the error if Outlook is already running most likely means Outlook and your app are running in different security contexts. Outlook is a singleton, so it attempts to connect to the already running instance. COM system however will not marshal calls between processes with different security contexts.