Workbook_Open sub won't run when I open the workbook?

Make sure your Private Sub Workbook_Open() subroutine is pasted inside of the This Workbook object and not in a Module, Form, or Sheet object.

Interesting. In 2009 a conflict with conditional formatting of the sheet to open is described, as in vbforum post.

It seems that this bug still exists in excel and prevents the workbook_open event from being fired. I have a workbook (old XLS-binary format) that simply does not fire the event in Excel 2003 and 2007 but does in 2013. I deleted all conditional formatting from the first worksheet but could still not get the workbook_open procedure to run in elder Excel-Versions.

A Workaround, I use in distributed workbooks is to use a local variable and a second event in the workbook as follows:

''
' private variable
Private wbOpenEventRun as Boolean

''
' procedure to be called by excel when workbook opens
Private Sub Workbook_Open()
    wbOpenEventRun = true
    ' perform tasks
End Sub

''
' the selection change event fires usually.
' performance is not reduced
Private Sub Workbook_SheetSelectionChange(ByVal Sh As Object, ByVal Target As Range)
    If Not wbOpenEventRun Then Workbook_Open
    ' perform tasks in reaction of selection change events, if required
End Sub

The solution I found was running the below code and then the "Open" event worked.

Sub EventRestore()

    Application.EnableEvents = True

End Sub