Next time you see this error: “This document can’t be opened because it’s too old.” Here is the fix!
I know this is an old thread, but I ran into the problem today. Apple support was only “Load it in the old ’09 and export it again”. They even suggested trying Microsoft products to convert it! Amazing! Anyway, if you’re interested, there is at least a hack to get it to work. Haven’t written a script to do this in general, but it worked for me.
1) Make a copy of your file, say blah08.key to blah09.key
2) in the new copy, blah09.key, control-click and “Show Package Contents”
3) There is a file called index.apxl (or possibly index.apxl.gz). If the .gz, then double-click and you get the without the .gz (and delete the .gz version)
4) Control-click the index.apxl, open with “Other” and choose TextEdit
5) In the big mess at the beginning (first couple lines), there is key:version=”72007061400″. Change this to key:version=”92008102400″
6) Save the file, and exit TextEdit
7) Rename the new copy, blah09.key, without the .key part – blah09. You’ll get a complaint about removing the extension – do it anyway.
8) Now it’s a folder! Control-click the folder blah09, and compress, making a blah09.zip.
9) Rename blah09.zip to blah09.key – again a complaint, but do it anyway.
Poof! Openable again!
Why Apple doesn’t include this easy fix, I have no idea.
Teaching Adventures 