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Since the latest Firefox update, it hangs immediately at startup. Now it never works, while other browsers always work. This is a fully updated Windows 10 computer. Even when it does work, Firefox's special tabs - About, Close Firefox, Restore session - are often big trouble; and it seems possible one of these may be the problem now. When Firefox is working. it either closes slowly or not at all, bringing always problematic "Firefox is already running - Close Firefox" messages. When one Firefox window is closed, Firefox always keeps the window that is causing trouble in the first place. So, two things. 1) Firefox doesn't work at all. If you fix this problem with an update, the update must start immediately because clicking on "Download Update" too will be hung. 2) You have terribly problematic special tabs which I have named above. It is my opinion that you cannot fix them - you have to rebuild them from scratch - otherwise they would be working properly right now. I have fallen back on Microsoft Edge which always works. Firefox is never working. Think about it.

When I open Firefox, I get Welcome to Firefox each time. I asked this question earlier and received this response:

This sounds like Firefox is not saving the profile/setup changes between launches. I’d check that Firefox isn’t running in a temporary/new profile and that the profile folder is writable.

You could also try creating a new Firefox profile and see whether it launches normally there.

I do not know how to do any of this, especially since I cannot open Firefox. Please advise.

Thank you.

t takes 4 or more time to open Firefox browser. Each time I get a message that said Firefox is not responding and this locks up the programs. I reboot the systems each time and this does not help to open Firefox browser. What is causing this malfunction and how to fix it?

Hello,

I have the following error message......."The Application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sestrace.exe tool for more detail?

This error message pops up when I click on the Firefox icon. How do I correct this error message?

Thank you.

macOS Tahoe 26.6（Intel Mac）でFirefoxが使用不能になっています。

【症状】 設定画面や一部のaboutページ（about:networkingなど）は開く 新しいタブを開くと非常に遅い、または開かない アドレスバーで検索してもグルグルのままで結果が出ない about:support は表示されない about:config も開けなくなった アドレスバーにURLを入力してEnterすると消えてしまう

【試したこと】 トラブルシューティングモード → 改善せず 新規プロファイル作成・別プロセス起動 → 同じ症状 完全アンインストール（AppCleaner使用）＋再インストール → 改善せず ベータ版（158.0b1）・安定版（156.0.1）・Nightly すべてで同じ症状 about:config で以下を変更 → 改善せず network.http.http3.enable = false network.dns.native_https_query = false network.dns.disableIPv6 = true

DNS over HTTPS オフ プロキシ設定を「なし」に変更 ハードウェアアクセラレーション関連の変更 ユーザーライブラリ内のFirefox関連フォルダをすべて削除して再インストール

【ターミナルでのエラー（重要）】 textFailed to launch tab subprocess @MachCheckInListener TimedOut Failed to launch gpu subprocess @MachCheckInListener TimedOut Failed to launch socket subprocess @MachCheckInListener TimedOut Failed to launch utility subprocess 完全再インストール後も同じエラーが再現します。

【環境】 macOS: Tahoe 26.6 CPU: Intel Safari: 正常に動作

プロファイルや拡張機能の問題ではなく、子プロセス（content process）の起動自体が失敗している状態です。 ご確認よろしくお願いいたします。

PLEASE HELP! One day last week, Firefox for my PC disappeared and it seems that Duckduckgo has taken over. I have used Firefox on my PC for a few years and occasionally use duckduckgo as my browser. Now I cannot find Firefox. It is up-to-date, as of last week.

Please Help RhonCa

"every time I try to start Firefox (after it has been shut down for say?15 minuets, may be less ) it just hangs up and will not open my main home page. If I open another browser, Brave or Microsoft they go directly to my home page. If I log off my computer and then back on to my computer then the Firefox browser will open up my main home page. I have no idea what I have done to make this act this way.

This morning I reset my PC, and upon doing so Firefox would just not work. Anytime I tried booting up firefox it would for a split second show the browser than revert to a screen where its just the firefox logo, where upon clicking it would become unresponsive

I've uninstalled and reinstalled twice both times completely clearing out firefox data from across my pc, i've tried to make new profiles, i've cleared out caches etc, yet anytime i try boot it up it still doesnt work

i've spent the past 6 hours just looking through fixes and still, nothing works every other browser works fine, aside from firefox

Hi all,

Version 153 in general seems to be more buggy than previous.

• The most affected bug now is opening links in new tabs will endlessly show the loading animation in the favicon tab area, and the page will be blank failing to load the content.

• No choice but to restart Firefox in order for it to function again.

• Also, every time relaunching Firefox gives the "Firefox is already running" message pop up.

• This started happening after updating to version 153.

Firefox 153.0.1 (32-bit) Windows 10 - 22H2

Thank you in advance

I have had problems with the latest FF for Mac for a week or so. Not opening. I deleted and reinstalled it, and the problem continues. It crashes my system and I have a spinning wheel that required a hard restart. What's going on? Running Tahoe 26.5.2

Beginning with September 2026, Mozilla Firefox browser - version 115 - does not work on Win7 anymore, although mozilla.org says that it should work until March 2027. Any explanation or solution? (I won't use Win10 or later versions ever.)

The problem: Version 115 can be installed, but after that Firefox browser does not work at all. Not only as internet browser, but even "settings" cannot be open. It's a dead program.

I installed Maxthon instead of Mozilla, because the Chinese browser supports Win7. This older version of the Windows is still perfect (!) for everything I use: internet, videos, Open Office, etc. However I have to select between ad blockers and browsers. My printers also works on this version of Windows.

When I cannot use Win7 anymore on the internet I will choose Linux instead of Win10 or later versions.