Folders.Item(FolderName).Folders : Error: System.Runtime.InteropServices.COMExceptions: The attempted operation failed. An object could not be found

Question

I'm very new in vb.net and outlook add-in, working on a project to build an outlook add-in (VSTO using VisualStudio 2017) where I'me getting this error for which im not getting any clue even after hours of googling, may be im not in the right direction. Thats why Im here to ask for your assistance. Thanks

Here is the error I've got, and I've pointed the line in the code where the error appears.

Error: System.Runtime.InteropServices.COMExceptions: The attempted operation failed. An object could not be found.

Update:

I was testing a little bit and found the if I don't rename the root folder problematically in this line dFolder.Name = "X" + dName , dName = dFolder.Name rather rename name manually within outlook add data file section then the full function works fine without any error.

Note: the purpose of this code is to copy emails from one folder to another where both root folder name is same because the destination folder is just a mirror copy of source folder And for this emails were not copying if the both folder name is same, That's why I had to rename the destination folder when i'm adding to Store Session so that system can identify the source and destination folder as two different location. I don't know why its not getting the rename value in dFolders = oNspace.Folders.Item(dName).Folders . please help.

.

Public Shared Sub SetSrcAndDst(Src As String, Dst As String)
    Dim oApp As Outlook.Application
    Dim oNspace As Outlook.NameSpace

    Dim sFolders As Outlook.Folders
    Dim sFolder As Outlook.Folder

    oApp = Globals.ThisAddIn.Application
    oNspace = oApp.GetNamespace("MAPI")
    sFolders = oNspace.Folders.Item(Src).Folders

    Dim oStores As Outlook.Stores
    Dim oStore As Outlook.Store

    Dim dPath As String
    Dim dName As String

    Dim dFolders As Outlook.MAPIFolder
    Dim dFolder As Outlook.MAPIFolder

    oStores = oApp.Session.Stores
    oNspace.AddStore(Dst)
    dName = ""

    For Each oStore In oStores
        dFolder = oStore.GetRootFolder
        dPath = oStore.FilePath
        If dPath = Dst Then
            dName = dFolder.FolderPath
            dName = dName.TrimStart({"\"c})
            dFolder.Name = "X" + dName
            dName = dFolder.Name
        End If
    Next


    '''
    ''' Getting error in this below line (dFolders = oNspace.Folders.Item(dName).Folders)
    ''' System.Runtime.InteropServices.COMExceptions: 
    ''' The attempted operation failed. An object could not be found.
    '''

    dFolders = oNspace.Folders.Item(dName).Folders

    For Each sFolder In sFolders
        For Each dFolder In dFolders
            If sFolder.Name = dFolder.Name Then
                Call CopyMail(sFolder, dFolder)
            End If
        Next
    Next
End Sub

($exception).StackTrace

 at Microsoft.Office.Interop.Outlook.FoldersClass.get_Item(Object Index)
 at AutoBackup.ThisAddIn.SetSrcAndDst(String Src, String Dst) in E:\AutoBackup\ThisAddIn.vb:line 56
 at AutoBackup.SettingsForm.PstConfirmBtn_Click(Object sender, EventArgs e) in E:\AutoBackup\SettingsForm.vb:line 37
 at System.Windows.Forms.Control.OnClick(EventArgs e)
 at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
 at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
 at System.Windows.Forms.Control.WndProc(Message& m)
 at System.Windows.Forms.ButtonBase.WndProc(Message& m)
 at System.Windows.Forms.Button.WndProc(Message& m)
 at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Answer 1

The error is very unambiguous - the folder with the given name does not exist.

As a test, loop through all root folders to make sure the folder with the given name is really there:

for each vFolder in oNspace.Folders
  MsgBox fFolder.Name
next