What add-ons are they, there may be alternatives or compatible versions that have not been picked up by the add-ons manager. Some add-ons may never be updated.

To downgrade to Firefox 3.6.* you can uninstall Firefox 4, but do not select the option to "Remove my Firefox personal data". If you select that option it will delete your bookmarks, passwords and other user data.

You can then install Firefox 3.6.* available from http://www.mozilla.com/en-US/firefox/all-older.html - it will automatically use your current bookmarks, passwords etc.

To avoid possible problems with downgrading, I recommend going to your profile folder and deleting the following files if they exist - extensions.cache, extensions.rdf, extensions.ini, extensions.sqlite and localstore.rdf. Deleting these files will force Firefox to rebuild the list of installed extensions, checking their compatibility, and reset toolbar customizations.

For details of how to find your profile folder see https://support.mozilla.com/kb/Profiles

Thanks very much for the link to the download! One of the add-ons I wanted to keep most was Sitelauncher, which allows access to dozens of bookmarked sites in a few keystrokes. By not deleting my personal data, firefox saved everything I needed. Thank you again!

If my heart had actually stopped, as it could have, when I found that I no longer had my AVG Security protection, expensive lifetime updates to my Garmin GPS, Turbo Tax for my 90% complete taxes, and a few other "unimportant" life enhancers, I could not have written this THANK YOU! Return to 3.6 was without a hitch, and I have all my personal info saved. I really don't think it would have required a lot to let us know, before we "upgraded", what we would lose in 4.0.

Many thanks, again.

cmiller, there is a version of SiteLauncher for Firefox 4 available from the developers home page - http://www.donesmart.com/sitelauncher

Thank you dear wizard, thank you! I "upgraded" to Firefox 4.0 today, only to discover a world of hurt. I had landed in a foreign land where nothing looked familiar and I had to search my way to where I thought I should be heading. The terrain was rough and the going was rather more complicated than it should have been. No yellow brick road to guide me. I longed for home! Trudging along, I made my way through the worldwide web, when I found a man named Tony, who seemingly as summoned appeared out of nowhere. He showed me my way back to the familiar landscapes I had learned to love. A few clicks of the mouse and there it was, in all its glory. Home again!! THANK YOU DEAR WIZARD!!

Firefox 3.8 would be the answer. Combine the features and layout of the familiar 3.6 version and combine it with the speed improvements of 4.0 and I would be a very happy camper. Using a rather weak wireless signal, I could definitely notice a serious speed increase with 4.0, but there were just too many daily use items that did no longer function to warrant sticking with it.

How do I uninstall Firefox?

https://support.mozilla.com/kb/uninstalling+Firefox

Can I install version 3.6.8? Is there a specific location to find this version?

http://www.mozilla.com/en-US/firefox/all-older.html