I have the same problem. i got a pop-up suggestion in Firefox itself(enclosing screenshot). I am also providing the link to the Mozilla help page I was led to-http://support.mozilla.com/en-US/kb/The+bookmarks+and+history+system+will+not+be+functional?style_mode=inproduct

I have still not used it due to lack of time but will do it soon & also update the post then.