Question

I want to prevent user to save the workbook with the same name as it is opened with, and to offer SaveAs option.

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
If ThisWorkbook.Name = "abc" Then
Cancel = True
SaveAsUI = True
End If

Also tried

 If ThisWorkbook.Name = "abc" Then SaveAsUI = True

This code doesn’t work. SaveAs dialog doesn’t appear.

Next try

If ThisWorkbook.Name = "abc" Then ThisWorkbook.ReadOnly = True
'Error - can't assign to read only property.

Answer 1

If you want to test for a particular filename only – say abc.xlsm then the code below will stop the Save (but pass SaveAs) then set the ReadOnly attribute to False so Save can’t be used again on this file in this session

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
If Not SaveAsUI Then
    If ThisWorkbook.Name = "abc.xlsm" Then
        Cancel = True
        ThisWorkbook.ChangeFileAccess Mode:=xlReadOnly
    End If
End If
End Sub