NSKeyedUnarchiver Exception, No Idea

FROM : Philip Dow
DATE : Thu Jun 08 21:37:15 2006

Hi,

I have a problem that I'm totally in the dark on. A user is testing a 
beta product that changes the way persistent data is stored. I had 
been using XML files, I am now using a keyed archive. The product 
must convert the user's data from the one format to the other.

As far as I am aware, the conversion goes fine. I'm inquiring about 
that right now. But once the conversion is complete, the application 
freezes trying to read the new data in its keyed archive form. The 
following is logged to the console:

"Exception raised during posting of notification.  Ignored. 
exception: *** -[NSKeyedUnarchiver initForReadingWithData:]: 
incomprehensible archive version (-1)"

I have no idea what that means or what would cause it. Google doesn't 
offer much, and the docs only say "The method decodes the system 
version number that was archived in data prepares the NSUnarchiver 
object for a subsequent invocation of decodeObject."

What's going on?

-Phil