Question

What am I doing wrong here?

Declare @starttimestamp datetime = getdate();
RAISERROR(N'Code not valid until %s', 16, 1, CAST(@starttimestamp AS VARCHAR));

Produces an error saying Incorrect syntax near 'CAST'. and Incorrect syntax near '@starttimestamp'. Expecting SELECT or (

Answer 1

You can’t perform a function within the raiserror command. Convert your date to a string first, like this:

Declare @starttimestamp datetime = getdate(),
        @TextDate  char(19)
select @TextDate = convert(char(19),@starttimestamp,120)

RAISERROR(N'Code not valid until %s', 16, 1, @TextDate)