Firefox Support Forum

I routinely record short screencasts with Kazam, and I can't watch my own videos after posting them on sites like GitHub because Firefox says "Video can't be played because the file is corrupt". Or for example when I upload them to sites like ezgif to convert them to a GIF, which works just fine because, well, the file is not corrupt. Other browsers like Chromium play them just fine.

Apparently the "OpenH264 Video Codec provided by Cisco Systems, Inc" is properly enabled in my system. This has been happening to me for months or years, but only today I decided to open a thread here.

There are two things here:

1. Firefox can't play the file. I'm sure there's some sort of misconfiguration on my side, or bad defaults, or a missing plugin, or similar. 2. Firefox shows a misleading message. The file is not corrupt! The root cause is something else.

Any advice on how to fix the first one?

I'm using 64-bit Linux Mint 20.3 LTS, and the latest version of Firefox from the repositories (101). Suddenly, for no reason I know, my default profile has started crashing immediately on trying to run Firefox. A small window comes up with the error message

XML Parsing Error: not well-formed Location: chrome://browser/content/browser.xhtml

     <button when-cofnection}"secure-cert-user-overridden"="" <="" pre="">
and then a line of ------^  where the ^ indicates between the t and the i of cofnection
Yes, I emphasise that I HAVE copied the error message carefully, including the mismatched bracket pair and the cofnection rather than (I assume) connection
I've managed to get a working version of Firefox by creating a new profile and using that (as in for posting this request for help), and I do have a recent backup of my bookmarks, but it will be a royal PITA if all my logins and passwords have disappeared. I don't want to go any further than this without some guidance, as all the messages I've found detailing how to fix this seem to make the assumption that I'm running Windows. 
Can anybody help, please?
</button>

Firefox says I need a video codec to play a video (that is aparently somewhere on the page). It does NOT tell me what video, what video format, or what codec I need. How do I find out what codec I need?

Firefox version: 101.0 (64 bit) OS: Fedora 36

Whenever I attempt to access DRM content such as netflix or spotify I am notified that the WidevineCdm plugin has crashed. I'm running firefox version 101.0.1 on Kubuntu 22.04, I am running the debian package release, but I had this issue with the snap version too. I've submitted crash reports, but they're all "EMPTY: no crashing thread" (https://crash-stats.mozilla.org/report/index/20af09a5-6bc4-4719-9242-38f5c0220614 here's one).

Hi,

is there a config option to prevent the showing of user/pw proposals when opening a website for which user account data is saved? When i'm logging into a website with already saved user data, i get account proposals (as ff saves the data "per domain", say if you have 3 accounts to one website, e.g. a test user, an administrator and a cms administrator, they are all presented where needed content may be...) see pict. I would like to opt out this behavior, as i have more than one website with 2 or more accounts.

-- cu

jth

I was using Firefox on windows 10 laptop, everything was synced with my account. Now after switching to Ubuntu I can't see my bookmarks, Just an empty toolbar. Now I don't have access to my old laptop, I sold it.

Any help?

I am trying to download a spreadsheet file which has a .xlsx extension. Firefox insists on downloading the file (my default action) but I want to be given the option to open in my spreadsheet program (Libreoffice).

Looking in Settings and scrolling down to Files and Applications -> Applications, there are other spreadsheet formats present but not one for .xlsx. How do I add the "Always Ask" option for .xlsx files?

Libreoffice is the default system application for opening these files.

Firefox allow to disable access to canvas for lowering fingerprinting, it's cool !

But as web developer : i like to ask this access before try to using it,

Something like :

1. Do you alllow canvas ? 2. Show the browser part 3. Wait for user answer 4. It's OK : download PDF done with canvass 5. It's not OK : shown an error to user.

To avoid such situation (see screencast)

For some reason, whenever I load a pdf from within Firefox, I get a new tab with the regular toolbar displayed on top of pdf files, but the document itself is completely blank (see attached screenshot). This issue just started today and I assume it was a result of an update, since I don't recall making any changes to my settings (I'm using Firefox 101.0.1 on Ubuntu 20.04).

I've tried opening multiple files from a variety of sites with the same result. All of them open fine using my system's pdf viewer, as well as from within Chromium. I've tried disabling my plugins, putting Firefox into safe mode and resetting all the handlers, to no avail. Any help would be much appreciated.

browser.sessionstore.resuming_after_OS_restart = false. My browser still restores on os restart. Startup -> Restore previous windows and tabs is unchecked browser.sessionstore.max_resumed_crashes = 0 browser.sessionstore.restore_on_demand = false browser.sessionstore.resume_from_crash = false

I do not and will not manually close my browser session every time I want to shut down my computer in order to get it to do what it's supposed to. Linux sends SIGTERM to all running processes on shutdown. Firefox isn't handling this correctly, obviously, because if it was, then my settings would be getting respected. SIGTERM is the standard signal sent to windows that need to close gracefully and are expected to still be functional.

NOTE: Do not provide windows-specific support to this thread. I am not running firefox on windows, and I do not possess a windows computer or license.

I'm trying to load a temporary add-on on my browser, but when I click the button "Load temporary add-on", nothing show up.

I tried to look for errors in the console or debugging tool, but nothing. With snap, I removed with the purge option my Firefox and install it again, but the issue still appears.

Some technical details: Ubuntu 22.04 LTS Firefox version 101.0.1 (64-bit) Mozilla Firefox Snap for Ubuntu canonical-002 - 1.0

A long time ago, I saw a list of open tabs in all windows, not just in one window, as it is now. (By the way, Google has added such a feature to Chrome. Clicking on the arrow allows us to see any open tab and navigate to it.) I am currently using Tab Manager to search for a tab. But the tab manager is not the best option because it is too slow to open and requires too many resources. Can I restore the old behavior to see tabs in all windows?

Firefox has become very slow for some two weeks om my desktop with Linux Xubuntu 18.04. Some sites can be approached without problems except for the speed, other sites are opened after some time, but freeze so that scrolling and clicking on links won't work. I tried to find an answer in the Settings......

Hello,

I am running Firefox v101.0.1 (64-bit) on Linux (Pop!_OS, installed as a flatpak). I am using the default system theme in dark mode, though switching to the Firefox dark theme or other themes does not change anything. When I allow the Menu Bar (File, Edit, View, etc.) to be present, the browser tabs on the next line are aligned correctly, going all of the way to the left. When I uncheck the Menu Bar, however, a gap appears to the left of the tabs. I have not seen this behavior on Firefox in other environments (Debian, RHEL, Windows), and I'm wondering if there's a way I can remove that gap. I have attached screenshots showing how the tabs are aligned with and without the Menu Bar.

Thanks so much!

Hi, I'm using version 101.0.1 (64 bit) for Ubuntu 22.04. When I open a link of a pdf file, the file is displayed in the built-in viewer, since I chose "Open in Firefox" in my settings. But then if I click the download icon nothing happens. If I click the print icon and choose "print to pdf" in the popup, then clicking on "save" does nothing and I have to click "cancel" to dismiss the popup.

Actually there is no way to save a pdf file but setting PDF app to "Ask always" and then open it with "System handler", but then the file is saved into the default download folder, even though I selected the checkbox "Always ask me where to save files" in my settings.

EDIT: the issue was solved by installing the following packages, as shown in this question :

xdg-desktop-portal xdg-desktop-portal-gtk

I've checked a couple of the "similar topics" before posting here. I'm not sure if I am having the same problem or something else.

Back Story: I have a "few" windows and tabs open in FireFox. I would finish what I was doing, shut down and then the next time I booted up and loaded FireFox, all sessions would be restored and all log ins honoured (kept). That is: I was still logged in.

(Moving to now) Yesterday I powered up and ALL sites were logged out. About 20 log ins were needed. Hmmmmm... gmail, and the rest.

"Ok... something happened. No problems, things should be ok from now. I've logged in, so all is sweet."

Today I power up: All logs ins lost. Had to go through it all again.

Gmail is throwing security alerts at me hand over fist. Yeah, that is good in some ways. I get that part. But I've logged in.

Seems - my thoughts - that the cookies aren't being saved. But why? I haven't touched them or their settings.

Yes, I did do a clean out of older cookies. But left the gmail ones, and other sites I know I use. I have `adblocker ultimate` installed.

Now I am logged in, if I open the `cookies` and look I should see them there for the sites to which I am logged in - yes?

To be clear: When I am done, I do NOT `exit` FireFox. All windows, tabs, sessions are left. I just shut down the machine. Then next time I load FireFox and they are re-loaded and log ins are maintained.

Hi, I hope someone can help me. I am an author and sell my book through KDP Amazon. Firefox is my default browser but will not let me log in to KDP. No problem with other websites including Amazon.com When I open the KDP log in page it accepts my email address but the password button has a row of asterix right across the window. I cannot delete whatever is in there or change the password via the forgotten password route. Thus to sign in to KDP I have to use an alternate browser. With both Opera and Chrome I can sign in with no problems. I have added a screenshot of the KDP log in which illustrates the problem. Grateful for any solution to this irritation. Thanks, Paul

An automatic update of Firefox which resulted in a "quit/create new profile" choice has removed all my bookmarks

Of the four profiles stored in "about:profile" three are identical (ie. have only the default bookmarks stored) and one, generates a "quit/create new profile" message.

The "bookmarksbackup" folder (in /home/user/.Mozilla/Firefox/zs1jki8t.default) is empty.

The "import/backup" option (in Manage Bookmarks) offers nothing to choose. There is no 'list of dated automatic backups.'

Firefox did not create an "Old Firefox Data" folder on the desktop.

Browser privacy "strict". "Never remember history" was selected.

Running Firefox in Manjaro (Linux)

Help.

Hi, Just installed Ubuntu on a new laptop, with Firefox. No add ons.

Have changed my homepage to www.duckduckgo. Have changed my default search engine to duckduckgo. In about:config my browser.startup.homepage says www.duckduckgo.

Have also changed browser.startup.homepage_override.buildID to www.duckduckgo.com and browser.startup.homepage_override.mstone to www.duckduckgo.com

But STILL, every time I start Firefox, I'm taken to google.com. Please cn someone tell me how to stop google coming up when I start Firefox.

Thanks, Ivan