Err.Source

This approach allows you to have a custom error-numbering strategy without fear of conflicting with native errors (or errors generated by other workbooks or applications.)

link - stackoverflow.com/questions/69370099/what-numbers-should-be-used-with-vbobjecterror/70283901#70283901 
Public Sub Test_Handler() 
   On Error GoTo ErrorHandler 
          
   Debug.Print 1 / 0                   ' 11, Division-by-zero  
   Kill "C:\Doesn't-Exist.txt"         ' 53, File not found 
   Err.Raise 11, "Custom"              ' 11, User cancelled  
   Err.Raise 53, "Custom"              ' 53, User paused  
   Exit Sub 

ErrorHandler: 
   Call GlobalHandler 
   Resume Next 
End Sub 

Public Sub GlobalHandler() 
Dim sDesc As String 
          
   Select Case Err.Source 
      Case "Custom" 
         Select Case Err.Number 
            Case 11: sDesc = "User Cancelled the process" 
            Case 53: sDesc = "User has paused" 
         End Select 

      Case Else 
         sDesc = Err.Description 
   End Select 
          
   Call MsgBox(sDesc) 
End Sub