Editing a GUI form using JPA

Hi all,

After a lot of time, I'm trying to come back to Java development. I
have an Ant-based Java SE project using Swing and EclipseLink JPA
2.1 originally developed in Java 8 and NetBeans 8.2. I'm now using
Java 17 and NetBeans 25 (I have 26 also installed, but I don't think
this has to do with 25 vs. 26). On opening a GUI component that
invokes an EntityManager I get this error:

Other GUI components not involving DB connection (like the main
window, with a JFrame and a classic dropdown top menu) can be opened
and edited without any problem.

The project, however, apparently clean and builds OK. I've replaced
the original EclipseLink JPA 2.1 library in the project for the
global EclipseLink 2.2.3, but still I keep getting the same error on
GUI editing. Any hint about where to start to look?

TIA

--
Ricardo Palomares (RickieES)
https://github.com/RickieES
https://sourceforge.net/u/rpalomares/profile
http://stackoverflow.com/users/1185157/