Upgrading a database from SQL Server 2005 to 2012 uncovered a syntax error
John is right that the updated syntax error message you get:


  Msg 1034, Level 15, State 1, Procedure trigger
  Syntax error: Duplicate specification of the action "UPDATE" in the trigger declaration.


This is absolutely because the trigger is specified as FOR UPDATE, UPDATE. This syntax was allowed in older compatibility levels but not in modern ones.

In fact, I have tested this and the syntax was allowed in 80 compatibility mode (SQL Server 2000), but not in 90+. I've updated my canonical answer about compat level 80.

(As for why it's not a documented breaking change, well, shrug. You'll need to approach Microsoft directly if you want a meaningful answer to that one.)

As for the trigger itself, here's how I would write this:

UPDATE t
  SET t.datetime = GETDATE()
FROM dbo.table1 AS t
INNER JOIN dbo.table2 AS t2
ON t.id = t.id;


The syntax error might be a more strict parsing of the word table, not sure. If that really is the name of your table, you should change it, or [put it in square brackets].