Can you please test if the update 3222 fixes this issue?
You can download a ZIP file from this link update-3222.zip
You need to unpack this ZIP archive into .ganttproject.d/updates folder in your user home directory so that the result file structure looked like this:
.ganttproject.d/updates/
└── update-3222
├── ganttproject
└── VERSION
.... other updates
Make sure that all the previous updates suggested by the Updater are installed.
GP 3.2 is expected to show version 3222 in the About dialog.
I’m having the problem that initial poster is having where a copy is failing and logging the following failure in the log:
java.io.IOException: Failed to save the project file
at net.sourceforge.ganttproject.io.GanttXMLSaver.save(GanttXMLSaver.java:116)
at net.sourceforge.ganttproject.GPTransferable.createDocumentFlavor(GPTransferable.java:94)
You probably need to install update 3240.
I am not sure why this fails, because the bug was fixed in 3230, which you seem to be using. Try installing 3240 anyway.