This occurs with .Net/VB6 interop when you show a VB6 form with a Web browser control on it before you show a .Net form.  There are several alternative solutions:
  1. Use amServer mode, the last argument to REAPI.Init, if you are using a web application or other non-interactive use. For example,
    Change this:

    REAPI.Init("MYSERIALNUM", "user", "password", 1, "", AppMode.amStandalone);

    to this

    REAPI.Init("MYSERIALNUM", "user", "password", 1, "", AppMode.amServer);
  2. Show a .Net form (such as a messagebox) before calling REAPI.init.
  3. Make a call to the Win32 function “oleinitialize” (which is what #3 would do indirectly).
If the application is for an interactive app then use #3 as shown below:

'Declare this API function to iniitialize COM.
Private Declare Function OleInitialize Lib "ole32" (ByVal reserved As Integer) As Integer

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

       Try
           'MsgBox("Click to start RE")
           'or

           OleInitialize(0) 'only needed if no UI shown before init
           moapi = New BBREAPI7.REAPI
           moapi.Init("wre11111")

       Catch ex As Exception
           MsgBox(ex.Message)
       End Try

End Sub


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