How to report an error from a SQL Server user-defined function

November 15, 2022 by Tarik

You can use CAST to throw meaningful error:

create function dbo.throwError()
returns nvarchar(max)
as
begin
    return cast('Error happened here.' as int);
end

Then Sql Server will show some help information:

Msg 245, Level 16, State 1, Line 1
Conversion failed when converting the varchar value 'Error happened here.' to data type int.