Updated again. It picked up 0.4.5fremantle17 correctly this time. The autosave error is gone. And I do see a .autosave file under /home/user/.xournal directory.

However, I am still experiencing the other problems. Can't do any explorer related job within xournal. such as Open, Save as, export. Xournal simply quits when I hit those menu items. Any suggestions? Thanks Anidel!