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The Problem An intermediate signing certificate, used by Mozilla to sign add-ons, has expired. This causes Firefox to consider add-ons signed with that certificate to be untrusted. The issue is being tracked in Bugzilla 1548973 and on Mozilla's blog. Solution 0: Update Firefox to 66.0.5+ or 60.6.3+ ESR Mozilla has released Firefox 66.0.5 for desktop and ...


91

Open your firefox "profile directory" Official docs how to do that: https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_how-do-i-find-my-profile Or just open: Linux: ~/.mozilla/firefox/<profile> OSX: ~/Library/Application Support/Firefox/Profiles/<profile folder> or ~/Library/Mozilla/Firefox/Profiles/<profile ...


55

The intermediate code signing certificate expired. This means that all add-ons signed with the cert are no longer trusted. In this case the browser is doing it's job. Mozilla will need to get the add-ons resigned and/or push a new cert out. Work is in progress to fix it. There is no resolution at this time unless you are on a developer code branch which ...


51

Happy to report that I was able to find a solution that I provided here: https://github.com/Thiht/markdown-viewer/issues/62#issuecomment-277702230 I've also copied it here for reference: On Linux, you'll need to create a new MIME type here: ~/.local/share/mime/packages/text-markdown.xml With the following content: <?xml version="1.0"?> <mime-...


38

The horizontal tab bar can be hidden with the following steps: Confirm or Create: Linux: ~/.mozilla/firefox/<profile name>/chrome/userChrome.css Windows: %AppData%\Mozilla\Firefox\Profiles\<profile name>\chrome\userChrome.css macOS: ~/Library/Application Support/Firefox/Profiles/<profile name>/chrome/userChrome.css Add the Following code ...


38

According to the Multi-Account Container plugin page, you can use Ctrl + . to open the panel. Then simply press the down arrow (or tab) and enter. Ctrl + . (period) keyboard shortcut is available to open the containers panel. You can then use tab and the enter keys to open new container tabs. After Ctrl + . you can also use the numeric keys in order to ...


33

I think this may interest others as well. ANSWER UPDATE (as of 2020) By now there's a lot of cool and interesting addons that do the job in great way, let me mention some of my favorite in a brief list: Firefox Color This imho is really THE DEFINITIVE ONE and A MUST HAVE! Not only it lets you deeply customize almost everything of Firefox GUI the way you ...


30

As of version 7 of the Containers extension, ctrl+shift+1-9 works without any further add-on. From the release notes: Set shortcuts in the add-on preferences panel: Ctrl + Shift + {Num} Which containers correspond to which number can be configured in the add-on preferences. As mentioned in other answers, ctrl+., tab also works. On MacOS it's cmd+shift+{num}...


22

I am assuming that you are asking about Adblock Plus. I cannot answer your question for other extensions, some of them implemented the Adblock Plus filter syntax in a slightly broken way. Yes, running Adblock Plus in a whitelist mode is possible. It is somewhat awkward however, the user interface support for this feature is still very lacking. First of all ...


20

Yes, there is a setting in About:config, its name is xpinstall.signatures.required. Double-click on the preference name so that its value is set to false. Now you can install unsigned extensions in Firefox. A browser restart is not needed.


17

There is a way. It's not super official, but basically you can unpack browser/omni.ja, edit the keybindings in chrome/browser/content/browser/browser.xul, repack it, delete startup cache and it will work. Alternatively, you can compile your own firefox and then you don't need to unpack the binary, if you consider unpacking and repacking more hacky, than ...


16

Building on edymtt's answer, I've created a userscript which disables only specific keyboard shortcuts. You can add more shortcuts to disable by adding keycodes to the keycodes array, or restrict which sites to apply it to by replacing the @include tag with one or more patterns. Install using greasemonkey. // ==UserScript== // @name Disable ...


16

Open about:config and change the value browser.display.background_color to the color of your choice. I'm using #595959 (neutral gray). This works with blank tab or "Firefox Home". Sadly, opening tab quickly or when the browser is on heavy load will still result of a white flash. If you don't know how to use about:config please read https://support....


15

Mozilla have now implemented a default zoom setting, although it's only available through about:config. You can change the pdfjs.defaultZoomValue in about:config to change the default zoom. Set it to a number for a number (no percent sign) for a given default percent zoom. Other possible values are page-width, page-height, page-fit and auto. https://github....


14

I want the tab bar to auto hide when there's 1 tab and appear when there's multiple. Not the same as the question but this is about the only Google result right now for 57+ so for those who need it in userChrome.css #tabbrowser-tabs, #tabbrowser-tabs arrowscrollbox { min-height: 0 !important; } #tabbrowser-tabs tab { height: var(--tab-min-height); } #...


13

For folks looking how to unblock elements they manually added themselves, you can click the uBlock icon, click the gear icon in the top left corner to go into the 'dashboard'. From there, go to the 'My Filters' tab and it will show you a list of all elements you've blocked manually. Manually blocking elements is pretty handy for all those annoying social ...


12

Since Firefox 58 it is possible to disable keyboard shortcuts override per web site. "Override Keyboard Shortcuts" and many other permissions are available in "Page Info -> Permissions" (under info icon in URL bar). Keyboard override was introduced in Firefox #380637


12

On the Firefox addon page search for your desired addon. Download Addon Continue to download Right-Click -> Save Link As... -> save the .xpi file Installing Addon Drop the addon in the adress bar.


12

Update: Now it is possible to do it directly in the url bar, asking for the special page about:restartrequired about:restartrequired It opens a page with a button to restart firefox that should preserve pages, tabs and windows. Fast Internal answer: Press ShiftF2, write restart in the opened bar, then press enter. On old versions, e.g. the 41.0.2, it was ...


12

This issue is due to a mass expiration of add-on certificates. As others have mentioned, a fix is in the works. To temporarily re-enable add-ons, you can navigate to about:config and set xpinstall.signatures.required to false. This will re-enable any add-ons installed that have expired certificates, but it is not recommended to keep enabled long-term. I ...


11

I had to manually edit my ~/.mozilla/firefox/<PROFILE>/mimeTypes.rdf. This review of the addon says: For linux users, try to add "md" to .mozilla/*.default/mimeTypes.rdf this line : mdin text/plain section :) Hmm. I couldn't find a text/plain section, but I found this page is helpful: If there is not yet an existing RDF node for 'text/plain' ...


11

As Wladimir pointed out the .xpi file is simply a ZIP archive put together in a particular way. Open it with WinRAR, 7-zip or rename it to .zip and open it with your OS's default tool. EDIT: (It appears that Mozilla's addons page no longer has this type of "Install" button, so this method won't work.) To get ahold of the .xpi file use https://...


11

I had a similar requirement and found two solutions to the problem: If you do not mind paying for the service use FoxyProxy Plus. The free version of FoxyProxy should also work fine for this. You can define rules (even more advanced, e.g. based on current IP address): http://getfoxyproxy.org/fpplus/ More generic - Generate a local Proxy Auto Configuration ...


11

The solution to disable automatic updates without running Firefox is as follows (OS is Windows): Edit the file prefs.js, located in %APPDATA%\Mozilla\Firefox\Profiles\xyz.default\ which usually translates to C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles\xyz.default\ (Note: username and xyz will vary) Make sure the line user_pref("app.update....


11

Firefox 60 actually has flag browser.urlbar.openintab in about:config. Setting it to true accomplishes what you want. Tried and true.


10

There is a way to do this without any addons: enter "about:config" into the URL bar. Press Enter. create a new entry with key=general.useragent.override and an empty string as a value. If you use an old version of Firefox, you also need to set the key general.useragent.enable_overrides to true. This way your browrer will not send any "User Agent" at all. ...


10

Software in general is unfriendly to us bilingual users. No web browser offers this functionality built-in. Some operating systems do, however. For example, on the Mac, switching your keyboard layout will switch default-dictionary used in any input field implemented using the OS-provided methods. Similarly, if you enter a full sentence into a text field, it ...


10

You can use the uBlock Origin's own logger for logging the network requests that got blocked or allowed in addition to the CSS rules that were affected by your filters. Please assist this official overview of the logger from the official uBlock Origin own Wiki page: https://github.com/gorhill/uBlock/wiki/The-logger Good luck.


10

There is a way to do this without dropping the container. You must go to the Multi-account container button in the top bar, then click to manage containers, then click the container where the wrong site was added by default. Then there is a button named manage site list and there you can (obviously) remove sites from being defaulted to that container.


9

Unfortunately, that particular UI customization is not currently possible via Firefox Quantum's supported add-on APIs; a proper solution will be possible once Bug 1332447 is resolved. Until then, VasyaNovikov's tweak to userChrome.css works, though editing that file is definitely an at-your-own-risk, not-officially-supported option.


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