Upgrading app from version 2.5.8 to 3.5.2

[Matthew Jew]

Hello,

I have an Mac OS X application that has been using version 2.5.8 for  
a long time.

I am making my first effort to instead use version 3.5.2.
My first attempt was just to replace the old version with the new  
version,
clean and recompile.

The compilation worked, but the app crashes when it runs.
It gets a 'EXC_BAD_ACCESS' error when it does its first attempt to
'CreateVarCharField' while creating a new database on disk.
(Or to create any field, I believe.)

I am sure I will be able to make the necessary corrections,
but I am asking in the interest of not having to re-invent the wheel:

Are there obvious changes to my code that I should be making in the  
transition from
version 2.5.8 to 3.5.2 that I am not aware of?

I have looked at the 3.5.2 sample applications, and they look  
otherwise the same
as they always have...

- Matthew