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?
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For the past few weeks I've been receiving numerous firefox crash reports & also when trying to open firefox an error indication that firefox is already open. I've never had this problem with firefox in the past, and have been an avid firefox user for many many years.

This occurred on my old desktop computer which died this week & is also occurring with my brand new, out of the box HP laptop computer (with ALL the windows updates and HP updates installed); The old computer used Windows 10 Pro, the new computer uses Windows 10 Home.

My old computer used just the windows defender for protection, but my new laptop comes with a 1 month trial of McAfee which I am using until the trial expires.

Firefox is (and was) my default web browser. The software and updates for firefox have always come from your official website and in a timely manner.

Could you please look into and resolve this issue?

Thanks so very much for being Mozilla Firefox!

A routine update from Firefox version 99 to version 100 caused Firefox to quit loading web pages, including the Settings page. Firefox appears to load normally but will not display any web page. The only thing that works consistently is Help/About Firefox. System: Lenovo E495 (AMD Ryzen 5 3500U) running Windows 10 Pro 21H2, build 19044.1706 Symptoms:

• Version 100 and higher work correctly in trouble-shooting (safe) mode
• Refresh does not resolve the problem
• Manually removing extensions (NoScript and Cookie AutoDelete) does not resolve the problem
• Uninstalling Firefox and existing profiles (all Mozilla folders in AppData/*), then making a clean install of version 100 does not resolve the problem
• Removing version 100 and reinstalling version 99.0.1 restores normal operation (repeatable with higher versions)
• Updating from version 99.0.1 to version 100.0.2 or version 101.0 does not resolve the problem
• I have not tried removing any Mozilla registry keys

About two days ago the cursor started disappearing / flashing when browsing in Firefox. It does not mater where the cursor is placed on the screen either the arrow or the hand will flash when moving. My system is a windows pro 10 system with all updates, last updates for W10 were made a couple of weeks ago, on Firefox whenever it asks to upgrade I do it.

Specifically: 1. If the mouse is stationary there is no cursor, if I move it the cursor flashes. 2. When the system comes up and I launch Firefox all is OK for about 2 – 3 minutes then the flashing begins. 3. If I stop Firefox ie “X” it and restart it the flashing occurs within 0 – 30 seconds. 4. If I restart the PC steps 2 & 3 repeat.

I have two other PC’s Windows Home, and Windows 7, as well as a laptop with Windows Home all with Firefox 101.0.1 all up to date all do not have the above issue. This does not occur with any other programs. I have two monitors, tried Firefox on each makes no difference same problem.

I have tried searching the internet and all I find is about Caret which is off. I uninstalled Firefox and installed it. That made no difference.

Any assistance will be appreciated.

Thank You

Bob

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).

When I look up the error message I get, everyone I see who got it can't open Firefox, but I can open it fine. For me, I have Firefox as my default browser and when another program (tModLoader on Steam) tries to open it, it gives me "Profile Missing," "Your Firefox profile cannot be loaded. It may be missing or inaccessible." I don't know if it gives the same error for other programs because I can't think of any programs that open my default browser. When I switch my default browser to Edge, the program can open Edge fine.

I'M trying to open Realtor.com and I get this message: Application error: a client-side exception has occurred (see the browser console for more information). Can't seem to fix it. Can you help?

Firefox 101.0.1 + extensions, Windows 11 22H2; both fully updated

Firefox has stopped saving the position of its window, looking to me like it is leaving space for my Windows taskbar but which is hidden.

Some online searching and I found that setting privacy.resistFingerprinting to false resolves the issue, but it is not a change I feel comfortable with and wonder if there is another solution. I have uBlock Origin installed so maybe I shouldn't be concerned.

I'm not sure if this is the cause but a few days after windows update my firefox crashes. I restart it and only screen opens and doesn't respond. Deleted Firefox, did fresh install. Firefox starts again but as soon as I log in my account, crashes again. Delete firefox and again fresh install. I don't login, I save 3 bookmarks and it crashes again. Delete firefox again and fresh install. But now firefox starts in the background (seen in task manager) but does not open a window. Download latest installer and try to install but now install says, "something went wrong" during the download. (could be the enterprise network here) this I tried a few times but no success.

So I download Firefox 101.0.1 ISO and install. But again running in background and no window.

HP Elitebook AMD Ryzen 7 PRO 2700 Vega Mobile Gfx

64bit Win 10 Pro 21H2 - 19044.1766

The latest update for Wondows 10 prevents Firefox (and Edge) from loading. Everything works fine once I've uninstalled the latest update so the problem is clearly theirs. I can't be the only person experiencing this problem but contacting Microsoft is next to impossible. I wonder if you can: 1) alert them to this issue; and 2) pressure them to fix it as constantly uninstalling the updates is a pain!

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.

Hello, My firefox has been randomly exiting for a longer time now. (I reopen Firefox it restores itself without any crash info) I've already tried reinstalling and using the cleaning tool. Now I wanted to remove my Addons, but one of them isn't deletable. It also has no name displayed which confused me... Furthermore, there are only "InstalTime12345678"-files in the crash reports directory (which I think aren crash reports). It seems to me the mysterious addon is installed through the policies. (I have a screenshot attached and uploaded them https://pastebin.com/59wzMDyv) This is my private computer and I never set those. Has anyone seen this before or can help? Thanks

Hello, Do not be tired

while i clicked on the normal Web page, Cursor is activate, And blink. it walks a lot on the nerves.

please solved this problem,

Thank You!

The rendering issue is not seen with Chromium (Linux) or Safari (Mac). I have no alternative for Solaris :-(

I have read the tips etc, reset everything, but there is no difference.

This has been happening for a a couple of years, getting progressively worse, It has got so bad, I have stopped using FF on all but Solaris now. (and I have been using it for a long long time).

I need someone to direct me to what information/data is needed to be collected so someone can comment. Do you have any favourite page load test web sites that I can send out put to you from?

Firefox version: 102.0 (64-bit) System: Windows 10 21H2

I recently downloaded a file that may have had some sort of virus or malware. The file came up negative in Windows Defender and Malwarebytes but I deleted it anyways; however, I still get a download popup every time I open Firefox telling me that "This file contains a virus or malware." I've cleared the download library and browser history (cookies, cache, etc.) but I still get the popup from the Firefox.

Is there any known fix for this? Thanks!

Discord hyperlinks will no longer open when Firefox Developer Edition is selected as my default browser. They open fine in both Firefox, Microsoft Edge, and Google Chrome when selected as Windows 11's default browser. When selecting my default browser it would show 2 instances of Firefox Dev but after uninstalling then reinstalling it there is only one instance in the default app list. I'm not really sure where to go from here. Maybe this is an issue with the latest version of Dev Edition or is this an issue with my Windows?

Thanks