Property:  Err.Description

Implemented in version 1.0
object. Description [ = string]

This property returns or sets a string containing a brief textual description of an error. The optional string argument lets you define the description of the error in your code. Otherwise, providing the generated error number relates to a VBScript runtime error, the Description value is automatically filled with a default description.

On Error Resume Next
Err.Raise 48
Err.Description = "My error"
Response.Write "Error type is '" & Err.Description & "'."

"Error type is 'My error'."