From the product page..."To connect to an Oracle database, PL/SQL Developer requires a 32-bit SQL*Net, Net 8, Net 9, Net 10, Net 11 or Net 12 version".
This really needs to go away! We require 64-bit Oracle for nearly all else now...maintaining both 32-bit and 64-bit Oracle Homes is an unneeded burden for our developer support teams...they don't understand the nuances and they honestly shouldn't have to at this point. For large company computing environments it's becoming commonplace that the developer isn't allowed to install and maintain their own PC software environment...and non-developers don't understand the complexities of maintaining the dual Oracle environments
What is the ETA for a 64-bit compatible PL/SQL Developer?