I'm not sure what you mean that you cannot open anything. No pages load? You could try troubleshooting that: Error loading web sites | Troubleshooting | Firefox Help.

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Here's the process to roll back:

First, I recommend backing up your Firefox settings in case something goes wrong. See Backing up your information.

Next, download and save Firefox 3.6 to your desktop for future installation. http://www.mozilla.com/firefox/all-older

Close Firefox 4, and uninstall it. Do not remove your personal data and settings, just the program.

Then finally you can reinstall Firefox 3.6. Unless you have installed an incompatible add-on, it should pick up where you left off. If there are serious issues, please post back with details.

Note: I haven't actually tried this myself!

I cannot even get Firefox 4 to load. I read your troubleshooting data - and tried to establish a new profile. Nope - that didn't work either. Start/Run/firefox.exe -ProfileManager wouldn't load - see attached image re result. I DO NOT like this new version of Firefox! My google search bar was far too wide - it took up the full width of the page - and my address bar shrunk to about 2cm in width. This is absolutely ridiculous! I tried to change this in the "customise" mode, but it didn't work. I then tried to "system restore" my pc back to the old version, but only succeeded in crashing my virus protection, ending in my having to cancel the system restore. I have a huge number of important bookmarks which I don't want to lose. I need action on this fast, as it is causing me massive inconvenience. I have been losing faith in Firefox for about the last 3 updates, and this is just the end for me!

@mariekirkwood, please see the backup instructions to avoid losing bookmarks. Also, system restore only restores Windows settings; it does almost nothing with/to Firefox or other non-Microsoft applications that store their settings outside of the Windows registry.

I have just read the bookmark backup instructions - which require firefox to load. IT WILL NOT LOAD FOR ME. I am left blundering around in Explorer and/or Opera. If I could be sure of my bookmarks remaining safe, I would reinstall Firefox. I cannot create a new profile to save my bookmarks to - the profilemanager will not load.

Good point. Back up your entire profile folder using Windows Explorer. Your bookmarks are in there.

https://support.mozilla.com/en-US/kb/Backing%20up%20your%20information#w_backing-up-your-profile

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

The new Firefox just plain sucks! If I wanted a damn ugly IE interface than I will run damn IE! Now we got DAMN FIREFOX copying the HORRIBLE IE that I HATE so much.. Think it is about time I start looking at alternatives like Opera because now Firefox has nothing IE doesn't but the lack of ActiveX. So why use Firefox?

Damn you developers if you want a damn IE than go use damn IE! Quit * around with what was the best damn browser which is now JUNK!

Edited for language - TonyE

It is unacceptable that you cannot just undo the last update. Why do I have to uninstall Firefox and then reinstall an older version? We should be able to just do an uninstall on the update. I hate hate hate Firefox 4.0.1. I've suffered through it all weekend and it is miserable. Why is it so simple and seamless to update into the new version, but so complicated to back out? (For the record, I wouldn't want to back out if the new update didn't suck!)

> Why do I have to uninstall Firefox and then reinstall an older version?

It might work without uninstalling Firefox 4 first. When you install Firefox 4, the installer is fully aware of what needs to be cleaned up from earlier versions, but the older Firefox 3.6 installer isn't expecting to find Firefox 4 so its cleanup routine may not be complete. I think the same is true of any major version upgrade, from any software maker. Uninstalling the higher version eliminates the risk of having inconsistent files that could cause the program to malfunction. I'm sure in some cases the extra step is not necessary, but the goal is to get it right on the first try and avoid additional problems, so I routinely recommend the uninstall.

All that you need to do is go to: http://www.mozilla.com/en-US/firefox/all-older and get the version you want... and install it... it will pick up you old stuff automatically... just did it on 3 computers running W7, with no problems. I did not need to delete or change anything... it worked just fine and now I have the older version on all my 'pooters'.

well if anyone knows how to get back to the old firefox,,and not the #4.0 please let me know...or else I am going to the Internet explorer,,which I have always hated,,but now it is better than the new firefox..the new,my social sites the profiles with graphics are all scrunched up in the middle I checked out Internet explorer and my pages are fine..still want the the last firefox back not 4.0,,,if something is not broken,,,LEAVE IT ALONE.....THEY really messed it up.....................orangebyrd@juno.com

@orangebyrd, start from the top of this page and look for "roll back". It's all there.

When someone has gone to all the trouble to set up their browser the way it suits them and then an updated version comes in and screws it all up so that the user has to spend more time resetting it up to suite them there is something wrong. The new version will not support some of the old settings. I don't have time to be redoing things every time some new employee has a bright idea. If it happens again I will not be using Firefox. Google Chrome it will be.

I want to roll back to an earlier version of Firefox. How do I backup my Firefox settings?

I hope to hell they come out with a "legacy mode" for FF4. I hate it, when 3.6 stops being supported, I will certainly move back to IE as it doesn't have such illogical button positioning and other bad changes.

You don't, when you uninstall 4, you simply don't choose to remove settings. Then when you reinstall 3.6, you will have all of your settings.

I am yet another user who is PISSED at the new FIREFOX 4 INTERFACE. What idiot was behind this?

AT LEAST HAVE AN OPTION FOR "CLASSIC" INTERFACE!!!

Firefox 4 is a downgrade and I'm returning to Firefox 3 until the zombies at Mozilla can pull their cranium out of their rectum. What happened? People at Mozilla used to be pretty sharp and did the right thing. Not anymore.

Hmmm - not a happy upgrade. How quickly the market changes. Maybe FF will disappear soon... Unless of course they really do listen as they claim

I lasted about 3 minutes with version 4, went back to 3.6.. What a blunder..

Yeah, Firefox 4 is the worst. Faster? Oh please. After I open about 3 screens in succession, it gets as slow as a turtle and finally freezes my whole computer. I have to shut everything down and start over. I hope using the suggested way of going back to a version of 3 (linked above) works for me! Actually, every time I download anything since 3.14 my computer got slower and slower. but I'll try 3.16 again. PLEASE - don't mess with stuff if it isn't broken! The previous version was FINE! I hate when computer geeks claim they're "making things easier." It only makes things harder for the rest of us.

• http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox