Excel.Application error in Visual Studio Express (Visual Basic)

Question

Using Excel 2010, Visual Studio Express 2013.

I have added the Reference Object Library in Visual Studio for Microsoft Excel 14.0

Imports Microsoft.Office.Core
Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim oXL As Excel.Application
        Dim oWB As Excel.Workbook
        Dim oSheet As Excel.Worksheet
        Dim oRng As Excel.Range

        ' Start Excel and get Application object.
        oXL = CreateObject("Excel.Application")
        oXL.Visible = True
    End Sub
End Class

However it gives me the following error:

Type 'Excel.Application' is not defined.
Type 'Excel.Workbook' is not defined.
Type 'Excel.Worksheet' is not defined.
Type 'Excel.Range' is not defined.

If I am using a wrong reference library for the excel version, please show how I can go about adding the proper object library to the list.

djv · Accepted Answer · 2016-09-30T16:10:57.547

You have imported the wrong namespace.

Change

Imports Microsoft.Office.Core

to

Imports Microsoft.Office.Interop

You will need to add a reference to Microsoft Excel 15.0 Object Library if you have not already (replace 15.0 with your version)

And instead of late binding, you can use the correct types

' using the fully-qualified class name as an example.
' Excel.Application would work just fine because Microsoft.Office.Interop is imported
Dim oXL As Microsoft.Office.Interop.Excel.Application
Dim oWB As Excel.Workbook
Dim oSheet As Excel.Worksheet
Dim oRng As Excel.Range

' Start Excel and get Application object.
oXL = New Excel.Application()
' note that you have proper intellisense now because oXl is no longer just an Object.
oXl.Visible = True

Lastly, to properly clean up your Excel reference, since it's a COM object, put this in your code where you are finished with the objects (when closing the form for example). Do this for each COM object you create.

System.Runtime.InteropServices.Marshal.ReleaseComObject(oRng)
System.Runtime.InteropServices.Marshal.ReleaseComObject(oSheet)
System.Runtime.InteropServices.Marshal.ReleaseComObject(oWB)
System.Runtime.InteropServices.Marshal.ReleaseComObject(oXL)

score 0 · Answer 2 · answered Sep 30 '16 at 15:37

Figured it out. The previous code was from https://support.microsoft.com/en-us/kb/301982. However, when I edited the code in the following manner the errors went away.

Imports Microsoft.Office.Core

Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

    Dim oXl As Object
    Dim oWB As Object
    'Dim oXL As Excel.Application
    'Dim oWB As Excel.Workbook
    'Dim oSheet As Excel.Worksheet
    'Dim oRng As Excel.Range

    ' Start Excel and get Application object.
    oXL = CreateObject("Excel.Application")
    oXL.Visible = True
End Sub
End Class

This is using late binding. Since oXl is an Object, you could put anything on that line `oXL.Visible = True`, for instance `oXL.Visib = True`, and you won't have any compilation error. But it will raise an exception at runtime. For this reason, people put `Option Strict On` at the top of their code, to point out this type of potential issue. — djv, Sep 30 '16 at 15:44

Excel.Application error in Visual Studio Express (Visual Basic)

2 Answers2