I am trying to combine a few Word docs and create one final doc using VB.NET as a part of a Windows application. But the Word document object is getting disconnected from RPC while trying to edit the final resulting document.

I am trying to copy content of one doc (just for example) and pasting it in the newly created doc
Desired Behaviour: The code will read a Word document, and copy its contents, and paste it into a new Word document.

Here is a code sample showing what I am trying to do,

Dim wordApp As Word.Application = Nothing
wordApp = New Word.Application
'Create a new final document
Dim finalDocument As Word.Document = Nothing
Try
    'Create a new final document
    finalDocument = wordApp.Documents.Add()
    'Adding Initial template doc
    Dim doc_Template_File As 
    Word.Document=wordApp.Documents.Open(doc_Template_FilePath)
    'Do some editing
    'Copy the content from one file
    doc_Template_File.Content.Copy()
    If finalDocument IsNot Nothing Then
        finalDocument.Range.Paste() 'Getting the exception at this line
        finalDocument.Range.InsertParagraphAfter()
        doc_Template_File.Close(SaveChanges:=False)
    End If
Catch ex As Exception
    'Handle exception
Finally
    ' Release resources
    If finalDocument IsNot Nothing Then 
    finalDocument.Close()
    If wordApp IsNot Nothing Then
        wordApp.Quit()
        helper.ReleaseComObject(wordApp)
    End If
End Try

I have tried to create the wordApp object in different ways too, as it was mentioned in some posts

Dim wordApp As Word.Application = Nothing
wordApp = New Word.Application

and

wordApp = Marshal.GetActiveObject("Word.Application")

On debugging I have observed that the object creation, opening the doc_Template_FilePath is successful. But exception is rising when I am trying to paste the content into the new doc (as mentioned in the code above) at finalDocument.Range.Paste() 'Getting the exception at this line. Here is the exception detail,

Source:: Microsoft.Office.Interop.Word Source:: System.Runtime.InteropServices.COMException (0x80010108): The object invoked has disconnected from its clients. (Exception from HRESULT: 0x80010108 (RPC_E_DISCONNECTED))`

Any suggestion or clues on how to resolve this? What am I missing here?