On Error GoTo error_handler
Workbooks.Open Filename:=("http://chart.finance.yahoo.com/table.csv?s=FAN.L&a=2&b=04&c=2014&d=2&e=21&f=2014&g=d&ignore=.csv")

On Error Resume Next
Workbooks.Open Filename:=("http://chart.finance.yahoo.com/table.csv?s=FAN.L&a=2&b=04&c=2014&d=2&e=21&f=2014&g=d&ignore=.csv")
On Error GoTo error_handler

If Dir(MyFileName) <> "" Then
        Workbooks.Open Filename:="C:123.xls"
    Else
        MsgBox "Spreadsheet could not be found in C:", vbCritical + vbOKOnly, "File not found"
    End If

Public Sub ErrorHandlingExample()

    On Error GoTo ErrorHandlingExample_Error

    Debug.Print 5 / 0

    On Error GoTo 0
    Debug.Print "No error"

    Exit Sub

ErrorHandlingExample_Error:

    Debug.Print "Error was found - " & Err.Description

End Sub