Have had this problem with Firefox for weeks.
Firefox loads but unable to do a search.   Message "Firefox has stopped working"   Sometimes works sometimes does not.   Sometimes loads sometimes does not.
I close then try to open again, same message or nothing works.
Sometimes opens with Browsec most times not.

Have deleted Firefox and reinstalled a number of times ( with or without Browsec ) same problem.
Tried different key settings same problem.
The old versions of Firefox worked fine for years.
Other browsers such as Brave, Comodo Ice Dragon etc work fine.
Any ideas as to why Firefox does not work - at least for me...
 

With the latest version of Firefox i can not access my online bank in the UK. Used to work fine and does now using Chrome, but not Firefox. Strange.

4 hours ago, Henryford said:

With the latest version of Firefox i can not access my online bank in the UK. Used to work fine and does now using Chrome, but not Firefox. Strange.

OP - Another issue is that internet downloads such as youtube etc.sent to my LINE account on my laptop ( have on both phone and laptop - same with Whatsapp ) try to open in Firefox and dont

 

I've given up on Firefox.  As it is now included with Win10 I use Edge as my secondary browser and Opera as my main.  Firefox, afer a week of using Edge to find any bugs,  has been deleted.

I'm using Firefox on Mac without issues. But haven't upgraded to Big Sur. Version is 84.0.1 (64-bit).

 

Actually no issues with either of browsers... FireFox, Safari Chrome or Edge.

Several things.

First off, go to portableapps.com and dl FF portable.

Install it in a directory away from everything else.  The beauty of this is all involved files will go below the dir you put it in, and will not read or put anything in your AppData directory or anywhere else, unless you direct it to.  If it all works well (enshallah!) you know it is something in your FF profile.  Save your passwds, bookmarks, etc then delete the entire AppData/Roaming/Mozilla subdir.  It won't hurt to have a backup of the whole subdir somewhere else,  should you want to refer to the old installation.

 

I have been using FF and it's ancestors since the 1990s.  Since it became FF I found that every so often the whole installation goes south and needs attention (things like uninstalling an add-on may not properly clean up or foo bar a json file, for example).

 

Worst case is somehow you picked up some crud and it is attempting to redirect what you are doing, or force you use a different browser that they've cracked.  Back before wifi became popular and we had to use internet cafes these were not unusual at all, but haven't seen such lately.  Rudest message I got was in Malaysia, pop-up said "Use IE, dummy!"

 

Let us know what happens.

 

I would advise against the portable version; even if it is for a test of the profile. A friend of mine often has problems with the portable version where the normal version works fine. Instead, I suggest making a new profile for a test:
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

It may be better to reset Firefox, which will automatically keep bookmarks and saved passwords. Resetting Firefox will delete extensions, so make a list to remember them for a new installation. How to reset Firefox:
https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

@Henryford
Regarding your online bank; do you get an error message? If so, tell us what it says. If you do not get an error message, please tell us what happens when you access the bank. If the problem occurs before logging in, tell us which bank it is.

2 hours ago, farang51 said:

I would advise against the portable version; even if it is for a test of the profile. A friend of mine often has problems with the portable version where the normal version works fine. Instead, I suggest making a new profile for a test:
https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

It may be better to reset Firefox, which will automatically keep bookmarks and saved passwords. Resetting Firefox will delete extensions, so make a list to remember them for a new installation. How to reset Firefox:
https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

@Henryford
Regarding your online bank; do you get an error message? If so, tell us what it says. If you do not get an error message, please tell us what happens when you access the bank. If the problem occurs before logging in, tell us which bank it is.

Error Message

 

Error:1007 ID:18.6f1d2017.1609206596.377716ce !!

I used to love FF, left at about the time that I was accused of being a backwoodsman as far as browsers are concerned (by FF admin). 

Try Vivaldi. Beats Opera, Edge and Chrome easily.

2 hours ago, Henryford said:

Error Message

 

Error:1007 ID:18.6f1d2017.1609206596.377716ce !!

That does not look like an error message from Firefox. If you give us the address of the website we can try to see if we get the error as well; however, usually, that kind of error is an error in the website's code.

OP = I have ditched Firefox altogether and trying Epic and Brave alongside my current 2 favourites.

Firefox has been my favorite browser, until Google didn't support it any more and Yahoo stepped.

 

Yahoo in itself has been a failure for the past 10 years, and so has everything they got involved with

Yesterday WhatsApp web stopped working on Firefox, it works fine on Chrome

 

A Google reveals that I'm not the only one with this problem, but that there are many, and no solution.

 

The last nail in the Firefox coffin for me.

OP - I have been using Commodo IceDragon and FlashPeak Slimjet for a long time now and for my needs they are suitable, only the latter is not supported anymore ( still works fine ).
I used Torch some years ago and suited me fine now it seems to have too many bells and whistles.

For video downloads I use 4K Video Downloader ( use to allow 10 videos at a time now only 1 without a small payment ), and ClipGrab.