Firefox

Firefox is a popular open source graphical web browser from Mozilla.

Installing

Firefox can be installed with the firefox package.

Other alternatives include:

Firefox Developer Edition — for developers

https://www.mozilla.org/firefox/developer/ || firefox-developer-edition

Firefox Extended Support Release — long-term supported version

https://www.mozilla.org/firefox/organizations/ || firefox-esr^AUR or firefox-esr-bin^AUR

Firefox Beta — cutting-edge version

https://www.mozilla.org/firefox/channel/desktop/#beta || firefox-beta-bin^AUR

Firefox Nightly — nightly builds for testing (experimental features)

https://www.mozilla.org/firefox/channel/desktop/#nightly || firefox-nightly^AUR

Firefox KDE — Version of Firefox that incorporates an OpenSUSE patch for better KDE integration than is possible through simple Firefox add-ons.

https://build.opensuse.org/package/show/mozilla:Factory/MozillaFirefox || firefox-kde-opensuse^AUR, firefox-kde-opensuse-rpm^AUR, firefox-kde^AUR or firefox-developer-edition-kde^AUR

On top of the different Mozilla build channels, a number of forks exist with more or less special features; see List of applications#Gecko-based.

A number of language packs are available for Firefox, other than the standard English. Language packs are usually named as firefox-i18n-languagecode (where languagecode can be any language code, such as de, ja, fr, etc.). For a list of available language packs see firefox-i18n for firefox, firefox-developer-edition-i18n for firefox-developer-edition and firefox-nightly- for firefox-nightly^AUR.

Note: Language packs are disabled on -nightly and -developer-edition due to frequent string changes that may cause crashes. To force a change to the UI language, you may need to set intl.locale.requested in about:config [1].

Add-ons

Firefox is well known for its large library of add-ons which can be used to add new features or modify the behavior of existing features. Firefox's "Add-ons Manager" is used to manage installed add-ons or find new ones.

For instructions on how to install add-ons and a list of add-ons, see Browser extensions.

Adding search engines

Search engines may be added to Firefox by creating bookmarks with the Location field using search URLs completed with %s in place of the query and the Keyword field completed with user-defined characters:

Location:
https://duckduckgo.com/html/?q=%s
Keyword:
d

Searches are performed by pre-pending the search term with the keyword of the specified search engine: d archwiki will query DuckDuckGo using the search term archwiki

Search engines may also be added to Firefox through add-on extensions, see this page for a list of available search tools and engines.

A very extensive list of search engines can be found at the Mycroft Project.

Also, you can use the add-to-searchbar extension to add a search to your search bar from any web site, by simply right clicking on the site's search field and selecting Add to Search Bar...

firefox-extension-arch-search

Install the firefox-extension-arch-search^AUR package to add Arch-specific searches (AUR, wiki, forum, packages, etc) to the Firefox search toolbar.

Plugins

Support for all plugins, including Flash Player, was removed in Firefox 85.[2][3]

Configuration

Firefox exposes a number of configuration options. To examine them, enter in the Firefox address bar:

about:config

Once set, these affect the user's current profile, and may be synchronized across all devices via Firefox Sync. Please note that only a subset of the about:config entries are synchronized by this method, and the exact subset may be found by searching for services.sync.prefs in about:config. Additional preferences and third party preferences may be synchronized by creating new boolean entries prepending the value with services.sync.prefs.sync. To synchronize the whitelist for the extension NoScript:

services.sync.prefs.sync.capability.policy.maonoscript.sites

The boolean noscript.sync.enabled must be set to true to synchronize the remainder of NoScript's preferences via Firefox Sync.

Settings storage

Firefox stores the configuration for a profile via a prefs.js in the profile folder, usually ~/.mozilla/firefox/xxxxxxxx.default/.

Firefox also allows configuration for a profile via a user.js file: user.js kept also in the profile folder. A user.js configuration supersedes a prefs.js. For a useful starting point, see e.g custom user.js which is targeted at privacy/security conscious users.

One drawback of the above approach is that it is not applied system-wide. Furthermore, this is not useful as a "pre-configuration", since the profile directory is created after first launch of the browser. You can, however, let firefox create a new profile and, after closing it again, copy the contents of an already created profile folder into it.

Sometimes it may be desired to lock certain settings, a feature useful in widespread deployments of customized Firefox. In order to create a system-wide configuration, follow the steps outlined in Locking preferences:

1. Create /usr/lib/firefox/defaults/pref/local-settings.js:

pref("general.config.obscure_value", 0);
pref("general.config.filename", "mozilla.cfg");

2. Create /usr/lib/firefox/mozilla.cfg (this stores the actual configuration):

//
//...your settings...
// e.g to disable Pocket, uncomment the following lines
// lockPref("extensions.pocket.enabled", false);
// lockPref("browser.newtabpage.activity-stream.feeds.section.topstories", false);

Please note that the first line must contain exactly //. The syntax of the file is similar to that of user.js.

Multimedia playback

Firefox uses FFmpeg for playing multimedia inside HTML5 <audio> and <video> elements. Go to video-test page or audio-test page to check which formats are actually supported.

Firefox uses PulseAudio for audio playback and capture. If PulseAudio is not installed, Firefox uses alsa instead.

Tip:

Firefox might not play video if audio is not configured. If you are intending to use PipeWire and WirePlumber make sure they are working properly

HTML5 DRM/Widevine

Widevine is a digital rights management tool that Netflix, Amazon Prime Video, and others use to protect their video content. It can be enabled in Preferences > General > Digital Rights Management (DRM) Content. If you visit a Widevine-enabled page when this setting is disabled, Firefox will display a prompt below the address bar asking for permission to install DRM. Approve this and then wait for the "Downloading" bar to disappear, you are now able to watch videos from Widevine protected sites.

Firefox can only play 720p video (or lower) with Widevine, due to not using hardware DRM playback. It is also required that the private mode browsing is disabled, for the window and in the preferences.

Open With extension

Install Open With add-on.
Go to Add-ons > Open With > Preferences.
Proceed with instructions to install a file in your system and test the installation.
Click Add browser.
In the dialog write a name for this menu entry and command to start a video streaming capable player (e.g. /usr/bin/mpv).
(Optional step) Add needed arguments to the player (e.g. you may want --force-window --ytdl for mpv)
Right click on links or visit pages containing videos. Select newly created entry from Open With's menu and if the site is supported, the player will open as expected.

The same procedure can be used to associate video downloaders such as youtube-dl.

Hardware video acceleration

This article or section is out of date.

Reason: Point 3. is wrong for Firefox 100. The RDD process must be used. (Discuss in Talk:Firefox)

Hardware video acceleration via VA-API is available under Wayland [4] and Xorg [5] [6].

To enable VA-API in Firefox:

Ensure that your video card is correctly configured for VA-API:
- See Hardware video acceleration for steps to verify and install VA-API drivers if required.
Ensure WebRender is enabled.
- Verify WebRender is enabled by opening about:support and then Compositing. It is enabled by default in GNOME and other desktop environments [7].
  - Ensure you are not running Software WebRender as that will not work as of August 2021 [8].
  - If necessary, Hardware WebRender can be force enabled by setting gfx.webrender.all to true.
Set the following flags in about:config:
Note: on Firefox 96 only setting media.ffmpeg.vaapi.enabled and media.rdd-ffmpeg.enabled to true should be necessary. Many below preferences no longer need to be set since the RDD sandbox was mostly fixed. However, some issues still remain [9].

Note: starting from Firefox 97, only setting media.ffmpeg.vaapi.enabled to true should be necessary.[10]

Note: As of Firefox 98, VA-API is blocked by RDD sandbox, but can be used by setting the environment variable MOZ_DISABLE_RDD_SANDBOX=1, although this is less secure. [11]
- media.ffmpeg.vaapi.enabled to true in order to enable the use of VA-API with FFmpeg.
- media.ffvpx.enabled to false to disable the internal decoders for VP8/VP9. This is necessary despite this bug being fixed [12][13].
- media.navigator.mediadatadecoder_vpx_enabled to true to enable hardware VA-API decoding for WebRTC [14].
- media.rdd-vpx.enabled to false to disable the remote data decoder process for VP8/VP9. Firefox attempts to use the RDD process for VP8/VP9 but the RDD sandbox blocks VA-API access [15]. Disabling the remote data decoder for VP8/VP9 process means VA-API will run in the content process instead. In Firefox 96 mostly working support for running VA-API in the RDD process was added.
  - Another possible workaround is to completely disable the RDD process by setting media.rdd-process.enabled to false, instead of just disabling it for VP8/VP9 as above.
- On Intel, in some cases VA-API might not work with the Intel iHD driver intel-media-driver. This might be workaroundable by using the Intel i965 driver libva-intel-driver. This workaround does not work anymore with Intel Iris Xe graphics, which are only supported by intel-media-driver. Luckily Firefox 96 introduced better support for the RDD Process, which should help with intel-media-driver. [16] [17] [18].
  - As a last resort, the content process sandbox can be disabled. However, this is a serious security risk and disables protection against attackers. It is recommended to leave the sandbox settings as default [19]. Nevertheless, to disable the content sandbox set security.sandbox.content.level to 0 [20].
Run Firefox with the following environment variable enabled:
- In Wayland, with MOZ_ENABLE_WAYLAND=1, see #Wayland.
- In X.org, since 94, Firefox will run in EGL mode by default which is sufficient [21].
  - For older releases, in X.org, enable EGL with MOZ_X11_EGL=1 or set gfx.x11-egl.force-enabled to true and gfx.x11-egl.force-disabled to false in about:config.

Warning: Disabling the content process sandbox is a security risk, starting in Firefox 96 initial support for working VA-API in the RDD process exists.

Tip:

As well as following Hardware video acceleration#Verification, one can confirm VA-API usage by checking Firefox VA-API logs. Run Firefox with the MOZ_LOG="PlatformDecoderModule:5" environment variable and check in the log output that VA-API is enabled and used (search for the "VA-API" string) when playing a video for example. Pay attention to these logs as they might indicate that only one of the two possible compositors described before (WebRender or OpenGL) works with VA-API on your particular setup.
To allow hardware decoding in YouTube, the video codec used must be supported by the hardware. The profiles supported by your GPU can be checked with Hardware video acceleration#Verifying VA-API and the YouTube codecs used can sometimes (if offered by YouTube!) be controlled with the h264ify or enhanced-h264ify extensions. Alternatively, you can install firefox-h264ify^AUR.

Note:

While NVIDIA's proprietary driver does not support VA-API, newer versions support DMA-BUF. Using libva-nvidia-driver^AUR, will allow for hardware video decoding on NVIDIA using CUDA. See the GitHub project for documentation on necessary environment variables and about:config changes.
Since currently there is no DMA-BUF support for VDPAU nor libva-vdpau-driver, this package will not enable hardware video acceleration in Firefox.
Currently Firefox's VA-API implementation can decode H.264/AVC, VP8 & VP9, AV1 encoded video. AV1 support requires FireFox 98+ [22].
Multi-GPU systems should automatically choose a suitable GPU for VA-API according to this solved issue.
Some videos (e.g. YouTube VR) may show a black image after setting media.ffvpx.enabled to false [23].
To workaround VA-API not working correctly in the RDD process, the RDD process sandbox can be disabled instead of moving VA-API to the content process as suggested above. This is not recommended since disabling the sandbox is a large security risk and disables protection against attackers. Set the environment variable MOZ_DISABLE_RDD_SANDBOX=1 to disable RDD sandbox.
AMDGPU users under linux-hardened may need to rebuild linux-hardened with CONFIG_CHECKPOINT_RESTORE=y due to mesa requiring the kcmp syscall. This may no longer be necessary due to this bug being solved.

Spell checking

Firefox can use system-wide installed Hunspell dictionaries as well as dictionaries installed through its own extension system.

To enable spell checking for a specific language right click on any text field and check the Check Spelling box. To select a language for spell checking to you have right click again and select your language from the Languages sub-menu.

When your default language choice does not stick, see #Firefox does not remember default spell check language.

System-wide Hunspell dictionaries

Install Hunspell and its dictionaries for the languages you require.

Dictionaries as extensions

To get more languages right click on any text field and just click Add Dictionaries... and select the dictionary you want to install from the Dictionaries and Language Packs list.

Tip: For Russian, the extension is packaged as firefox-spell-ru.

KDE integration

To bring the KDE look to GTK applications (including Firefox), install breeze-gtk and kde-gtk-config. Afterwards, go to System Settings and in Appearance > Application Style > Configure GNOME/GTK Application Style… choose 'Breeze'.
To use the KDE file selection and print dialogs in Firefox 64 or newer, install xdg-desktop-portal and xdg-desktop-portal-kde, then do one of the following:
- Set widget.use-xdg-desktop-portal.mime-handler to 1 in about:config. You should also change widget.use-xdg-desktop-portal.file-picker from 2 to 1.
- Launch firefox with GTK_USE_PORTAL=1 environment variable.

Note: Using GTK_USE_PORTAL=1 or setting widget.use-xdg-desktop-portal.mime-handler to 1 will result in Firefox asking to set default browser every time Firefox starts.

For integration with KDE MIME type system, proxy and file dialog, one can use firefox-kde-opensuse^AUR variant from AUR with OpenSUSE’s patches applied. Alternatively, integration with MIME types can be achieved by creating a symbolic link to the MIME database ~/.config/mimeapps.list from the deprecated ~/.local/share/applications/mimeapps.list that is used by Firefox. See XDG MIME Applications#mimeapps.list.
Extensions/add-ons may provide additional integration, such as:
- Browser integration in Plasma: requires plasma-browser-integration and the Plasma Integration add-on.

Tip: To prevent duplicate entries in the Media Player widget or tray icon, set media.hardwaremediakeys.enabled to false. This disables the media entry from Firefox and only uses the one from the Plasma integration add-on.

Tips and tricks

For general enhancements see Firefox/Tweaks, for privacy related enhancements see Firefox/Privacy.

Dark themes

Firefox should respect your GTK theme settings and your OS-wide dark appearance settings (as in the Appearance section of GNOME's settings or KDE system settings). If the later does not work, make sure to have a suitable xdg-desktop-portal package installed.

Starting with Firefox 68 you can make all the Firefox interfaces and even other websites respect dark themes, irrespective of the system GTK theme and Firefox theme. To do this, set ui.systemUsesDarkTheme to 1 in about:config [24].

As of Firefox 100, further control of the dark theme of web pages that opt-in (using the CSS media query prefers-color-scheme) and Firefox's own in-content pages is possible with layout.css.prefers-color-scheme.content-override. Setting this to 3 will follow the browser theme, setting this to 2 will follow the system wide dark-mode preference (ui.systemUsesDarkTheme as above, which defaults to 0 if the user has not changed the dark-mode preference or if a system does not support a system-wide dark-mode preference), while 1 and 0 will always force light-mode and dark-mode respectively. This setting can also be accessed through the user settings of Firefox under General > Language and Appearance > Website appearance.

Frame rate

If Firefox is unable to automatically detect the right value, it will default to 60 fps. To manually correct this, set layout.frame_rate to the refresh rate of your monitor (e.g. 144 for 144 Hz).

Memory limit

To prevent pages from abusing memory (and possible OOM), we can use Firejail with the rlimit-as option.

New tabs position

To control where new tabs appears (relative or absolute), use browser.tabs.insertAfterCurrent and browser.tabs.insertRelatedAfterCurrent. See [25] for more information.

Screenshot of webpage

You can Take a Screenshot by either using the screenshots button that can be added to the toolbar from the customize screen in the Hamburger menu at More tools > Customize toolbar, by pressing ctrl + shift + s or by right-clicking on the webpage. See [26] for more information.

As an alternative you can use the screenshot button in the developer tools, which can be added through the developer tools Settings menu, under the Available Toolbox Buttons section. The settings for the developer tools are accessible through the three horizontal dots located at the top right of the developer tools pane.

Wayland

More recent versions of Firefox support opting into Wayland mode via an environment variable.

$ MOZ_ENABLE_WAYLAND=1 firefox

To make this permanent, see Environment variables#Graphical environment and start Firefox via the desktop launcher like you normally would.

To verify it worked, look for Window Protocol in about:support. It should say wayland. The presence of x11 means you are running Firefox under Xorg display server, while xwayland means your system is running Wayland but executing Firefox as legacy X11 application.

If it is necessary to be regularly switching between Wayland and X.org, it may be useful to add a conditional to your shell's login startup script, e.g. ~/.bash_profile for Bash:

if [ "$XDG_SESSION_TYPE" == "wayland" ]; then
    export MOZ_ENABLE_WAYLAND=1
fi

Window manager rules

To apply different configurations to Firefox windows, change the WM_CLASS string by using Firefox's --class option, to a custom one.

Profiles

To start new Firefox instances, multiple profiles are required. To create a new profile:

$ firefox [--new-instance] -P

Class can be specified when launching Firefox with a not-in-use profile:

$ firefox [--new-instance] -P profile_name --class=class_name

Firefox Profilemaker can be used to create a Firefox profile with the defaults you like.

Touchscreen gestures and pixel-perfect trackpad scrolling

This article or section is a candidate for merging with Firefox/Tweaks#Enable touchscreen gestures.

Notes: Same solution. (Discuss in Talk:Firefox)

To enable touch gestures (like scrolling and pinch-to-zoom) and one-to-one trackpad scrolling (as can be witnessed with GTK3 applications like Nautilus), set the MOZ_USE_XINPUT2=1 environment variable before starting Firefox. On Wayland, MOZ_ENABLE_WAYLAND=1 may also need to be set.

Multiple home pages

To have multiple tabs opened when starting Firefox open a new window and then open the sites you want to have as "home tabs".

Now go to Preferences > Home and under Homepage and new windows click the Use Current Pages button.

Alternatively go directly to Preferences > Home and now under Homepage and new windows set the first field to Custom URLs.. and enter the pages you want as new home pages in the following format:

https://url1.com|https://url2.com|https://url3.com

Troubleshooting

Troubleshoot Mode

The command line switch -safe-mode starts Firefox in Troubleshoot Mode, which disables extensions, themes, hardware acceleration, the JIT and some other features for this session.

This mode can also be enabled by pressing on the hamburger menu while Firefox is open, clicking Help, selecting Troubleshoot Mode and confirming this on the modal dialog that appears. Please note this will require a browser restart.

This mode was previously named Safe Mode until Firefox 88.

Firefox refresh

Some issues experienced by users in Firefox may be caused by profile issues, such as corruption.

If you have ruled out other causes, it may be worth trying a new Firefox profile for testing purposes to see if this will resolve your issue. More information on how to create a new profile and switch between profiles can be found on the Firefox support page.

If this resolves your issue, you should switch back to your original profile and consider refreshing your Firefox.

Refreshing your profile will retain all browsing and download history, bookmarks, web form auto-fill data, cookies, personal dictionary and passwords, and will transfer them to a brand new profile without extensions, themes, extension data and preferences, among other data. A backup of your old profile will also be retained.

To refresh your profile, navigate to about:support, press Refresh Firefox and confirm this on the modal dialog that appears. about:support can also be accessed by pressing the Hamburger menu, selecting Help and then clicking More troubleshooting information.

More information on refreshing your Firefox, including further details about what is transferred to the new profile, can be found on the Firefox support page.

Disable hardware video acceleration

If you are having issues with hardware video acceleration in Firefox, e.g. in case of freezes or graphical corruption, start Firefox in Troubleshoot Mode for testing purposes to confirm that this is the issue. If this step resolves the issue, merely set media.ffmpeg.vaapi.enabled to false in about:config to disable hardware video acceleration, and restart Firefox.

Extension X does not work on some Mozilla owned domains

By default extensions will not affect pages designated by extensions.webextensions.restrictedDomains. If this is not desired, this field can be cleared (special pages such as about:* will not be affected).

Firefox startup takes very long

If Firefox takes much longer to start up than other browsers, it may be due to lacking configuration of the localhost in /etc/hosts. See Network configuration#Local network hostname resolution on how to set it up.

Misbehaving Firefox extensions, or too many extensions, may be another source of slow startup. This can be confirmed through the use of Troubleshoot Mode, which will disable extensions on restart.

A further cause of slow start-up may be a profile issue, such as corruption. For more troubleshooting steps around your Firefox profile see #Firefox refresh.

Font troubleshooting

See Font configuration.

Firefox has a setting which determines how many replacements it will allow from Fontconfig. To allow it to use all your replacement rules, change gfx.font_rendering.fontconfig.max_generic_substitutions to 127 (the highest possible value).

Firefox ships with the Twemoji Mozilla font. To use the system emoji font, set font.name-list.emoji to emoji in about:config. Additionally, to prevent the Mozilla font interfering with your system emoji font, change gfx.font_rendering.opentype_svg.enabled to false or remove /usr/lib/firefox/fonts/TwemojiMozilla.ttf (see also pacman#Skip files from being installed to system).

Setting an email client

Inside the browser, mailto links by default are opened by a web application such as Gmail or Yahoo Mail. To set an external email program, go to Preferences > Applications and modify the action corresponding to the mailto content type; the file path will need to be designated (e.g. /usr/bin/kmail for Kmail).

Outside the browser, mailto links are handled by the x-scheme-handler/mailto mime type, which can be easily configured with xdg-mime. See Default applications for details and alternatives.

File association

See Default applications.

Firefox keeps creating ~/Desktop even when this is not desired

Firefox uses ~/Desktop as the default place for download and upload files. To change it to another folder, set the XDG_DESKTOP_DIR option as explained in XDG user directories.

Changes to userChrome.css and userContent.css are ignored

Set toolkit.legacyUserProfileCustomizations.stylesheets to true in about:config

Middle-click behavior

To use the middle mouse button to paste whatever text has been highlighted/added to the clipboard, as is common in UNIX-like operating systems, set either middlemouse.contentLoadURL or middlemouse.paste to true in about:config. Having middlemouse.contentLoadURL enabled was the default behaviour prior to Firefox 57.

To scroll on middle-click (default for Windows browsers) set general.autoScroll to true.

Backspace does not work as the 'Back' button

According to MozillaZine, the Backspace key was mapped based on which platform the browser was running on. As a compromise, this preference was created to allow the Backspace key to either go back/forward, scroll up/down a page, or do nothing.

To make Backspace go back one page in the tab's history and Shift+Backspace go forward, set browser.backspace_action to 0 in about:config.

To have the Backspace key scroll up one page and Shift+Backspace scroll down one page, set browser.backspace_action to 1. Setting this property to any other value will leave the key unmapped (Arch Linux defaults to 2, in other words, it is unmapped by default).

Firefox does not remember login information

It may be due to a corrupted cookies.sqlite file in Firefox's profile folder. In order to fix this, just rename or remove cookie.sqlite while Firefox is not running.

Open a terminal of choice and type the following:

$ rm -f ~/.mozilla/firefox/<profile id>.default/cookies.sqlite

The profile id is a random 8 character string.

Restart Firefox and see if it solved the problem.

If it did not work, check if there exists a cookies.sqlite.bak file that you could use to manually restore the cookies.

Cannot enter/leave fullscreen

If Firefox detects an EWMH/ICCCM compliant window manager, it will try to send a WM_STATE message to the root window to request Firefox be made to enter (or leave) full-screen mode (as defined by the window manager). Window managers are allowed to ignore it, but if they do, Firefox will assume the request got denied and propagate it to the end user which results in nothing happening. This may result in not being able to full screen a video. A general workaround is to set the full-screen-api.ignore-widgets to true in about:config.

Related bug reports: Bugzilla 1189622.

JavaScript context menu does not appear on some sites

You can try setting dom.w3c_touch_events.enabled to 0 in about:config.

Firefox does not remember default spell check language

The default spell checking language can be set as follows:

Type about:config in the address bar.
Set spellchecker.dictionary to your language of choice, for instance en_GB.
Notice that the for dictionaries installed as a Firefox plugin the notation is en-GB, and for hunspell dictionaries the notation is en_GB.

When you only have system wide dictionaries installed with hunspell, Firefox might not remember your default dictionary language settings. This can be fixed by having at least one dictionary installed as a Firefox plugin. Notice that now you will also have a tab Dictionaries in Add-ons. You may have to change the order of preferred language for displaying pages in about:preferences#general to make the spell check default to the language of the addon dictionary.

Related questions on the StackExchange platform: [27], [28], [29]

Related bug reports: Bugzilla 776028, Ubuntu bug 1026869

Some MathML symbols are missing

You need some Math fonts, namely Latin Modern Math and STIX (see this MDN page: [30]), to display MathML correctly.

In Arch Linux, these fonts are provided by texlive-core and texlive-fontsextra, but they are not available to fontconfig by default. See TeX Live#Making fonts available to Fontconfig for details. You can also try other Math fonts. In case you encounter this bug [31] installing otf-latinmodern-math can help.

YouTube videos load but does not play. This also happens on other web browsers.

The factual accuracy of this article or section is disputed.

Reason: * If this applies to other browsers, then this info should be moved to the page corresponding with the component that is the root cause (PulseAudio?), and be linked to. See Firefox/Tweaks#Emacs_key_bindings for an example of this.

This solution verifies that PA is installed, only to just replace it with PipeWire. This should be solvable while keeping PA.
This Firefox issue was edited out of this section, but it appears to still be unresolved. (Discuss in Talk:Firefox)

Verify you have pulseaudio installed. While the video is being loaded, in a terminal application.

pulseaudio --kill
# If there is no autostart
pulseaudio --start

This should ensure the video plays (albeit without sound at first). You should be able to select another video on YouTube and be able to view the video with sound, as long as you do not leave YouTube's single-page application. Once confirmed that pulseaudio is the issue, replace pulseaudio with pipewire-pulse and re-login to see if it works. See PipeWire#PulseAudio clients for details.

Tearing when scrolling

Try disabling smooth scrolling in Preferences > Browsing.

Firefox WebRTC module cannot detect a microphone

WebRTC applications for instance Firefox WebRTC getUserMedia test page say that microphone cannot be found. Issue is reproducible for both ALSA or PulseAudio setup. Firefox debug logs show the following error:

$ NSPR_LOG_MODULES=MediaManager:5,GetUserMedia:5 firefox

...
[Unnamed thread 0x7fd7c0654340]: D/GetUserMedia  VoEHardware:GetRecordingDeviceName: Failed 1

You can try setting media.navigator.audio.full_duplex property to false at about:config Firefox page and restart Firefox.

This can also help if you are using the PulseAudio module-echo-cancel and Firefox does not recognise the virtual echo canceling source.

Cannot login with my Chinese account

Firefox provides a local service for Chinese users, with a local account totally different from the international one. Firefox installed with the firefox package uses the international account system by default, to change into the Chinese local service, you should install the add-on manager on this page, then you can login with your Chinese account now.

No audio on certain videos when using JACK and PulseAudio

If you are using JACK in combination with PulseAudio and cannot hear any sound on some videos it could be because those videos have mono audio. This happens if your JACK setup uses more than just stereo, but you use normal headphones. To fix this you simply have to connect the front-center port from the PulseAudio JACK Sink to both playback_1 and playback_2 ports of the system output.

You can also do this automatically using a script:

jack-mono.sh

#!/bin/sh
jack_connect "PulseAudio JACK Sink:front-center" "system:playback_1"
jack_connect "PulseAudio JACK Sink:front-center" "system:playback_2"

Keep in mind that the names for the sink and the ports might be different for you. You can check what your JACK setup looks like with a Patchbay like Catia from cadence.

Geolocation does not work

Recently, Google limited the use of its location service with Arch Linux, which causes the following error when geolocation is enabled on a website: Geolocation error: Unknown error acquiring position. Region-locked services such as Hulu may display a similar error indicating that your location could not be determined even though you have allowed location services for the site.

To avoid these problems, you can switch to use the Mozilla Location Service. In about:config change the geo.provider.network.url setting to:

https://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%

See FS#65241 for more details.

Right mouse button instantly clicks the first option in window managers

This problem has been observed in i3, bspwm and xmonad.

To fix it, navigate to about:config and change ui.context_menus.after_mouseup to true.

See [32]

Firefox window does not repaint after disabling or enabling compositing

Unset the environment variable MOZ_X11_EGL.

Related bug report: Bugzilla 1711039.

Firefox continuously asks to be set as default browser upon launch

There are a couple things you can try: if you are using a desktop environment, check if Firefox is set as the default browser in your system settings. If it is not, then set it, otherwise you can run the following xdg-settings(1) command, provided by the xdg-utils package, to query which browser is set as default on your system:

$ xdg-settings get default-web-browser

If no value is returned or it is not Firefox, then run this command to set it:

$ xdg-settings set default-web-browser firefox.desktop

If Firefox still asks to be set as the default browser, then it may be quieted if it is set to handle http and https URL schemes. To do so, run these xdg-mime(1) commands:

$ xdg-mime default firefox.desktop x-scheme-handler/http
$ xdg-mime default firefox.desktop x-scheme-handler/https

If those do not work either, check if you have set the environment variable GTK_USE_PORTAL (all values trigger the bug), in which case, unset it. Related bug report: Bugzilla 1516290. If that does not work or you did not set it, navigate Firefox to about:config, check if the variable widget.use-xdg-desktop-portal is set to true and, if so, set it to false.

If you wish to disable default browser check entirely, navigate Firefox to about:config and set browser.shell.checkDefaultBrowser to false.

Video stuttering

If you experience video stuttering and you notice that Firefox is only hitting one core at 100% when watching videos (especially higher resolution videos), this might help you.

Go into about:config and search for dom.ipc.processCount and change dom.ipc.processCount.file from 1 to a higher number. An ad hoc method to find a good number is to increase it one at a time until you get good results, but 4 seems to be a good value.

Bengali font broken in some pages

In most cases, installing the noto-fonts and making Noto Sans Bengali as defaults in Fonts and Colors settings solves it. However, in some social media sites, Bengali fonts may still be broken. In those cases, Mozilla provides a detailed guide on how to see all the fonts gets loaded in a page. By using Page Inspector, find out all the fonts that are being loaded on that particular page. Removing fonts other than Noto Sans from the system will resolve the issue permanently.

There will be some fonts that have been installed as dependency of other package. For example, chromium installs ttf-liberation as dependency, which loads itself in some Firefox pages automatically and breaks Bengali fonts on those pages. To solve this issue:

Warning: This will briefly put your system in an incomplete state. See System maintenance#Avoid certain pacman commands.

Temporarily forcibly remove ttf-liberation:

# pacman -R --nodeps --nodeps ttf-liberation

Launch Firefox and reload the problem website.
Install ttf-liberation once more, as it is a hard Chromium dependency:

# pacman -S --asdeps ttf-liberation

Web Speech API has no voices

Firefox uses for text to speech (tts) speechd. You can use the command spd-say "some test sentence" to test if it reads the text or spd-say -L to get a list of the voices. If there are no voices, too, you can install some with the package espeak-ng. If they do not work out of the box, you maybe have to configure them. You can use the spd-conf command or edit the config file .config/speech-dispatcher/speechd.conf. There should be the following lines active (without # in front of it):

AddModule "espeak-ng"                "sd_espeak-ng" "espeak-ng.conf"
DefaultModule espeak-ng