It is down to the developer of the add-ons to make them compatible. Some may have been abandoned and will never be updated. Check the Mozilla add-ons site or the home page of the extensions, some may already have been updated for Firefox 4.

Though not comprehensive, this link gives details of the compatibility of many add-ons - https://addons.mozilla.org/en-US/firefox/compatibility/report

How do I go back to the earlier version, Firefox 3.6xxx or whatever it was? I cannot operate without my Norton Identity Safe toolbar until they release a patch in May. Meanwhile, PLEASE!! I have to have my old Firefox back! You should have warned me BEFORE I installed this "latest and greatest" -- which it will be, once I have my Norton back on it.

Symantec need to update their Firefox add-ons so that they are compatible with Firefox 4. They have indicated that for Norton 360 they plan to release an update to Norton 360 to support Firefox 4 in early May - http://us.norton.com/support/kb/web_view.jsp?wv_type=public_web&docurl=20100720113635EN&ln=en_US

I do not know about the time scale for updates for other Norton products. Pending the update by Symantec, if you want to use the Norton add-ons you will need to downgrade to Firefox 3.6.

To downgrade to Firefox 3.6 first 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 the latest version of 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

Please give me a link to download my previous version of Firefox -- the latest in the 3.6 series, I believe -- anyway, I always had the latest version. I cannot operate for a month until Norton gets its toolbar extension compatible, and I do not appreciate losing something I depend on, like their identity safe toolbar.

A working version of 3.6, for this month, that's all I ask.

Many thanks.

For add-ons that haven't been updated yet, you may also want to try the Nightly Tester Tools to force them to work. Keep in mind though that this can compromise your browser's stability.

Thank you, i'll try it.

i guess the reason im having trouble is its not just one specific issue, it's many. the first is ff keeps popping up a box that says "it is important that you update now" it does this every time i launch firefox but only after ive been online a while, then it will crash, then it will pop right back up but this time 1/2 my tabs are missing (my home page is not set to firefox but to my yahoo, the box will just keep running and running and can never seem to connect to server. most importantly under half of my addons dont work. which includes the antivirus program (Trend Micro Titanium Security). Not having this addon is not an option for me especially if something happens and i do get a virus. downgrading back is a must but im such a beginner. i saw the list of files i should delete and saw how i shouldnt remove ff personal data..i just know if delete ff4 everything will close and short of writing all the files down by hand i dont even know where id find them. i tried clicking on firefox profile and nothing was there..probably not the profile they were referring to..as i said im a beginner..may i please have the link to downgrade back too ff3.6? or would a simple system restore work? carolyne cc ps.sorry to ask a question while replying..beginner here..lol

Do not use system restore, it can cause problems and may stop Firefox from working.

To downgrade to Firefox 3.6 first 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 the latest version of 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

I have this same issue, except not with Symantec... with Kaspersky URL advisor. Absolutely must have in order to operate safely. Can I use same instructions given for others to revert back to 3.6.??? And if I do so, will I automatically get my now non-functional add ons back? Thanks much!

Just download 3.6 and install without uninstalling 4 like i did.

i am happy now with my oldfirefox still giving me my extensions working.

i also had an upgrade fo 3.6 (3.6.17 now).

Now i'm waiting for the iextensions i like to use to upgrade themselves.

In my opinion firefox team should stop acting like trying to sell s.t. We already now it is fast, it is safe and good in any other way. They should keep developing without insistin' on installing new versions. Otherwise causes a panic mood. They should do managing social level of thinkings.