Catch multiple exceptions at once?

Question

It is discouraged to simply catch System.Exception. Instead, only the "known" exceptions should be caught.

Now, this sometimes leads to unnecce

Answer 1

How about

try
{
    WebId = Guid.Empty;
    WebId = new Guid(queryString["web"]);
}
catch (FormatException)
{
}
catch (OverflowException)
{
}