After upgrading to a very gay Firefox v3.6, I was annoyed that it disabled many of my working extensions.
To add to my annoyance, it didn't restore my window sessions correctly. I had heaps of windows opened over a period of many weeks and many of the pages were ridiculously difficult to find.
Luckily, I had the TabMixPlus extension installed. It automatically saves your sessions. I know, I know, Firefox does this automatically already. But Firefox only saves one or two sessions.
TMP saves up to a week by default. So it doesn't really matter how many times you open and close your windows, you can be sure its protected in case of a stupid update.
If you need to restore the sessions:
- Close your Firefox session (and make sure nothing important is opened). You may want to copy these instructions somewhere first.
- Find your profile folder
- Go into "sessionbackups"
- Find the latest "tabmix_sessions-***.rdf" file and copy it
- Go up a folder, delete/move/rename "session.rdf"
- Paste the file into "sessionbackups"
- Rename it to "session.rdf"
- Your sessions should be restored the next time you open Firefox
[ Source ]