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 cannot believe how bad this new version is. It should come with a huge health warning "Only update if you what to ruin your browser" Firefox PLEASE PLEASE PLEASE make it easy for me to undo this update and get back the previous version. Oh and whilst you are at it please also give the person who thought this update was a good idea some genuine feedback - test your update on real users before issuing it to everyone.

It is so bad I might even go back to (I can hardly bring myself to say this) Microsoft Internet Explorer - There, I have said it, I am ashamed to have said it but it had to be said - things are that bad!

Mozilla - If you want some specific feedback get in touch.

It's down to personal taste, I think Firefox 4 is much better that the previous versions.

Firefox is tested by real users, that is how the open source project works. Anybody can test the new versions, all development versions of Firefox are available for anybody to use.

OMG what have you done? This looks like Chrome. It works even worse! If I wanted to use Chrome I would have. This update is terrible. Fortunately I was able to back rev. Another move like that and I will be forced to go back to IE *visible body shudder*. That's how bad this version is. Not to mention the adds I've been using for a loooong time are "no longer compatible" with this ridiculous version. TIP: If it ain't broke, don't fix it. I will be scoping out any further upgrades before I hit the "install" button. Thanks for the "no warning". I used to trust any upgrades you pushed. No longer.

This upgrade is so awful I actually created an account to let you know of my dissatisfaction.

If you do not like the new UI, you can make Firefox 4 look and behave more like Firefox 3.6, for details see http://www.computertechtips.net/64/make-firefox-4-look-like-ff-3-6

Another way of looking at "If it ain't broke, don't fix it" is stagnation. That is what Microsoft did with IE6. In its day it was a reasonable browser, but Microsoft left it for quite a few years and so they fell way behind, leaving them to play catch-up.

I like Firefox 4, I think it is a great improvement over Firefox 3.6. People submitting comments using the feedback feature show that many others also like Firefox 4.

HUGE disappointment. Look/feel seems like it was designed by an 8th grader who got a low grade for the project.

Did anybody even bother to read any of the feedback? Did they do ANY user testing?

Today is 5/6. If this is not resolved by 5/13, I'm gone - if I can stand to deal with this sloppy, amateur regression that long.

Tony - thank you so much for trying to help so many of us, but I don't understand why Firefox doesn't address the problem that Firefox 4 is HORRIBLE and they are being flooded here with complaints about it.

WHERE IS A COMMENT FROM FIREFOX???

What a mistake it was to upgrade to 4.0 !!!

I am so disappointed in Firefox right now I am ready to go back to Microsoft. I seem to have more errors than I have ever had before When mozilla first came out I was a big fan but the last 2 versions have given me nothing but headaches. To many errors. I will still trek on but if it keeps up I am back to Microsoft :( which I detest with a passion unless I find something else :(

Hello, Now back with 3.6 Please whoever you are stop "FX*)^£$%^" with it.

Must admit I have had mega problems which no one has answered yet. I had reverted back to FF 3.6. Like others I hope FF will read these posts and sort something our soon or I too may have to go back to IE {i shudder at that thought)

I don't like this either. The only reason I haven't gone back to IE is that the links don't work. I'm about to go back to a previous version of Firefox.

I loved Firefox until today and now I hate it! Strong words yes, but that's the way I feel. This new 4.0 is crappy at best. I googled and found the downgrade--that is actually not a DOWNgrade, but and UPgrade from 4.0 The new version is ugly, very user UNfriendly and does not work with many of my add ons and I can't save my tabs to be instantly reloaded like I could before and the add on that would give me that option is not compatible with the new 4.0. So where are the advantages? If Firefox needs security and other upgrades fine, but don't go messing with the formatting or at least give us a version of a Classic formatting to choose from. When the old version runs out and whatever new version of Firefox is being offered has not had a greater improvement then I will be shopping for a new browser.

Cathy :(

I sadly have to agree. It mainly seems like a pointless upgrade for the sake of an upgrade. All the logic that existed previously has gone and browsing now is confusing and frustrating. Maybe it is quicker, but I haven't got past wtf is going on with this. Unless there is a very rapid retro upgrade I'm outa here and back to Safari! First rubbish upgrade from Mozilla, sorry guys, if it aint broke, leave it alone. AND - I too created this account to complain, not sure it will have any impact as Mozilla don't seem that concerned so far... maybe they are taking a leaf out Bill Gates Book... Cheers, Clive

It can be stagnation but change just for the sake of change is not improvement, either. I don't see a reason to move items around if it does not improve the product- why make users get used to a change if it makes no difference to performance? i.e.; why are the tabs above the toolbars now? it really makes no difference which position they are in but as long as people are used to one position, why slow them down by making them relearn where to look? That's the kind of change I find irritating.

Now change that would make Firefox stop gobbling CPU resources when it's been open awhile- that is change I would welcome!

Sadly, I have to agree with many of the assessments of FF4 above, even to taking the distasteful step of going back to IE, which I haven't used (outside of work) for years.

Specifically: Missing Menu Toolbar. DAMMIT! Stop trying to take a page from MS Office design. Stop trying to remove all WORDS from the interface. Maybe we're moving to a more and more illiterate world but you do not have to cater to it.

Adding the Menu Toolbar leaves me with a full inch of wasted space at the top of the browser. I just can't have that on my none-too-large laptop.

Without the Menu Toolbar, where's my "Favorites" link?? I use that for the 30% of my browsing that isn't prompted by my Google Gadget links (see below). Oh I'm sure it's there somewhere...but that's not the point. It's not an upgrade for me to have to (unnecessarily) relearn the interface.

Most of the gadgets on my iGoogle homepage, that I DEPEND ON, don't work with the browser. WTF?? It's only obscure sites like Slashdot, Techdirt, ESPN, and a bunch of prominent news aggregators. Needless to say, I'm not giving up the homepage I've configured and used for years to accommodate this update.

Please stop listening to hot-shit interface design "experts" who want a "clean" interface. Some of us don't mind clicking on a word, or words, that describe the function it links to.

Not. Happy. I'll be going back to 3.6 and if that doesn't work...IE. *gag*

oops, double post, my bad.

ps) I installed the NoScript add-on a while ago, and wanted to test the extent to which it might be responsible for some of these issues (specifically the Google gadget problem), but the "Add-on Manager" just takes me to some site promoting a bunch of add-ons.

What I'd like to see, and expected, was a page that showed what add-ons I have installed and the option to disable/enable them. Another wtf, I guess.