Error Converting NVARCHAR to DATETIME

I create a temp table

CREATE TABLE #Test(theDate DATETIME)

I use this query to insert data into the temp table

INSERT INTO #Test VALUES(CONVERT(NVARCHAR, '2016-09-30' 21))

It works on one database (SQL Server 2005), but gives error on another (SQL Server 2008). I can't remember the exact error, but it has something to do with 'Error converting NVARCHAR TO DATETIME'

Why is working on one database, but not another? Is there a special property to enforce error on mismatched type? I can't find information anywhere.