GanttProject without Java Oracle

I am responsible, within my company, for proposing a solution to use GanttProject without the use of Java Oracle.
I therefore opted for the solution proposed with Liberica JDK.
GP launches well but it is impossible to open a project .gan :

Likewise, for creating a new Gantt chart, I get the following error:

Thanks for your help.

GanttProject distro for Windows is bundled with Liberica Java Runtime. You don’t need to download anything besides the installer.