Firefox Support Forum

When trying to install any extensions on either the Mozilla Addons website or directly via the Extension settings, it fails to do so.

I've attached a screenshot of the Mozilla Addons website when it fails to install the extension. On some other addons that I've attempted in the past, it just shows the throbber forever.

I have checked the Multiprocess Browser Console and it says that it fails to move the file because it's locked (NS_ERROR_FILE_IS_LOCKED). I have also attached a screenshot of that.

Hi I am a longtime user of your browser. I have version 124.0.2(64 bit) installed on three devices. First thing I do on opening it is to click on "about", which normally updates the browser, before I do any browsing. In the last three weeks, however, it has not updated on any of the three devices, rather, it says "Failed to check for updates". I have tried the workarounds suggested at your Help center, and nothing has worked. What gives, may I ask? Thank you

Recently Firefox always has the error "failed to check for update". I have tried restarting my pc and running as admin. I am on windows 10.

I have been able to manually install the latest version by installing it over the top of my current install, how can I fix the error to be sure that my browser will auto update?

Thanks

I have uninstalled and reinstalled firefox and restarted my computer but it still will not load. When i first reinstall it it comes up but will not connect to the intenet.

I see my original question is now archived at https://support.mozilla.org/en-US/questions/1380948#question-reply I never closed it because I didn't know if my last process could really fix the issue. It didn't, not always. Over the years, there have been times when the issue would still pop up, but not as often as before (2022 and earlier).

I have a feeling that during an issue, FF is having difficulty setting up shop after starting up. Consequently, it is spending more time before it could become prepared to connect to the Net. I've come up with another "solution," which is deleting (or moving out) xulstore.json in the profile folder after exiting or before starting FF. You can create a batch command or script to execute the process.

So far, FF is connecting immediately after startup.

After just turning on my computer running Windows 10, I opened Firefox. I open 1 web site and noticed my computer showed a (16) prefix when loading Firefox. I opened the Task Manager and it showed that there were 15 instances of "firefox" running in the background. All showed a UAC Virtulization of "Disabled". But they also showed using 638.8MB of memory. I do not know whether these are necessary files that must run in the background or if the number of files indicates that my system has been hacked and someone else is in my system from outside. Any suggestions as to validity of these files running or how I might confirm that they should be running. I have noticed the number of excessive background files before but the number is never consistent which makes me fear I may have been hacked.

Recent issue, April 2024. Had version 124 Firefox on Win10 computer and went to Help - > About to have Firefox check for updates. This has worked just fine up until now. The message "Failed to check for updates." is shown in the About screen. I have uninstalled and re-installed Firefox with the same results. Have also un-installed Firefox, un-installed Mozilla Maintenance, then removed Firefox data from App Data folder in user directory, then re-installed with the same results. Also, now when I access a local media server, I keep getting the message "Firefox is installing components needed" and that never goes away. Any ideas?

I did an Upgrade to a version of Firefox that would bypass those "Your Browser Is Not Supported" messages that apparently come from "Cloud-flare." I figured [naievely!] that my addons would "port" to the upgrade. They didn't. Is there any way [e.g., a putative backup file, perhaps] that would allow this?

Thanks in advance...!

Please reply to --- The Gray Cat << tmc@att.net >>

I just switched to Windows 10 from Windows 7. Firefox was working fine, but now many or most pages are garbled; see screen-capture fragments at http://www.fenichel.net/firefox/. I tried a new Firefox 64-bit, but it crashed on most pages.

Hi, Before Firefox's Version 125.0.1 (64-bit) latest update I could download any file from my safe office environment, behind firewalls, VPN, ... Now despite of unchecking the "Block dangerous downloads" I'm still unable to download files. I have Windows 10 on my laptop.

Here are the steps: Click on a file, Save "File not downloaded. Potential security risk." Click on the message - Allow download The result is a file with content "HTTP Status 405 – Method Not Allowed".

Please help me to work the downloading again. I am aware of the safety but I want to switch off this feature.

Thanks in advance for help, Tibor

Prior to update 125.0.1 corporate intranet users could download PDF files from our Line of Business applications / Webpages. Today after the latest update the PDF files download but are corrupted. The site was added to the trusted webpage without improvement.

Adobe Acrobat Reader could not open ********.pdf because it is either not a supported file or because the file has been damaged

Hi, so on my office pc I work with firefox. I made an account specifically to store every bookmarks etc on that account so when my company updates something I'll always have my bookmarks. Unfortunately somehow since yesterday they all disapeared, and no I'm unable to recover them with the different methods that are foreseen on your website. please advise kr daniel

I can no longer log into my social security account using Firefox, but the login does work on edge. When I try login on Firefox, I get the following error message:

Bad Request

Your browser sent a request that this server could not understand. Size of a request header field exceeds server limit.

The initial web site is https://www.ssa.gov/. From there I hit "Sign in", and get to https://secure.ssa.gov/RIL/SiView.action using Edge, but get just the error message using Firefox.

There is another route, which is through https://www.ssa.gov/myaccount/. Hitting either account or sign in on that page will work on Edge, but gives the same error message on Firefox.

today 4/18/2024 firefox update. Now browser is slow. Task manager showing currently 15 firefox open, even though only one new tab is selected. It is causing laptop to overheat, fan is running constantly. Nothing else is open.