I have gotten into a state where I select the "Save All" option
on the File menu and a dialog appears that says "Cannot save".
No exception is thrown and no other info is available so it
is hard to debug what is wrong.

I checked and in NbTopManager.java, around line 740, I see this:

            descriptor = new NotifyDescriptor.Message(
                        MessageFormat.format (
                            NbBundle.getBundle
(NbTopManager.class).getString("CTL_Cannot_save"),
                            new Object[] {
((DataObject)ee.next()).getPrimaryFile().getName() }

However, in the Bundle.properties, CTL_Cannot_save is
defined as:

CTL_Cannot_save=Cannot save

I think it should be changed to:

CTL_Cannot_save=Cannot save {0}

so that the file that cannot get saved is displayed in the
error message.

Using my own build of FFJ, open and closed sources updated
on 6/26/01 around 8:00 am PDT.