Firefox add-on cannot be installed. How to install unsigned add-ons in Firefox
Many users did not like this innovation, including me. For example, I use several old, but still quite working add-ons, the development of which was stopped many years ago. And I myself modify some additions to suit my needs; naturally, after such changes, the digital signature becomes invalid. Fortunately, the developers then left an option in the browser settings that allows you to disable checking digital signatures installed add-ons.
Starting from version 48, the freebie is gone, Firefox no longer accepts this parameter. Regardless of its value, if you try to install any unsigned extension, you will see a danger warning and the installation will be blocked. But there is a way by which you can still install third-party extensions in Firefox browser.
First, you need to switch Firefox updates to the ESR (Extended Support Release) channel. This is an extended support version of the browser designed for use in organizations. Installs directly on top current version Firefox, all settings remain in place, nothing crashes.
Now go to the settings page by typing in address bar about:config. There we find the parameter xpinstall.signatures.required And double click switch its value to false. That's all, now you can install any updates, including unsigned or modified ones, without any problems. Another idiotic quirk from the “effective managers” of Firefox has been successfully overcome.
The 43rd version of Mozilla Firefox on the Stable and Beta channels blocks the installation of unsigned extensions.
To cancel signature verification for extensions, you can change the settings:
- In the address bar, enter about:config and go to the page;
- Click the "I promise I'll be careful" button on the warning page;
- In the "Search" field, enter the name of the parameter: xpinstall.signatures.require ;
- find it in the list and double click on it so that the value "true" changes to "false"
Disabling signature verification via custom scripts
In Firefox 48 for the Stable and Beta channels, Mozilla has removed the xpinstall.signatures.require setting. On the Dev, Nightly and ESR channels, as well as in the Firefox Unbranded build, which is stable version, the option is still available.
All extensions presented in the main Mozilla repositories are signed, unlike extensions from third-party sources.
Today there are many extensions provided by applications on the Github and Bitbucket development platforms, as well as older extensions that are no longer supported by developers and cannot be signed. All of them cannot be installed in Firefox Stable or Beta using standard means.
This method involves creating two files in the main directory where Firefox is launched.
1. config.js file
1.1. Create text file;
1.2. Paste the code into it:
//
try (
Components.utils.import("resource://gre/modules/addons/XPIProvider.jsm", ())
.eval("SIGNED_TYPES.clear()");
}
catch(ex) ()
1.3. Rename it to "config.js". Make sure it's called config.js and not config.js.txt;
1.4. Move it to the directory with Firefox installed:
- Windows - " C:\Program Files\Mozilla Firefox\" or " C:\Program Files (x86)\Mozilla Firefox\";
- Linux - " /usr/lib/firefox-<версия> " or " /usr/lib64/firefox-<версия> ";
- OSX - "/Applications/Firefox.app/ ".
These are directories Firefox installations default. They may differ depending on your installation settings or Linux distribution. It is important that the file is in the root directory of the program.
2. File config-prefs.js
2.1. Create a second text file;
2.2. Paste the code into it:
pref("general.config.obscure_value", 0);
pref("general.config.filename", "config.js");
2.3. Rename to config-prefs.js;
2.4. Move to " <корневая директория Firefox>\defaults\pref\"
For example " C:\Program Files\Mozilla Firefox\defaults\pref\";
2.5 Restart Firefox. 
You can now install signed and unsigned extensions in Firefox Stable or Beta.
What happens?
The code in the config.js file loads one of the configuration Firefox files and removes the information from the "Signed_Types" constant in that file. This constant specifies the types of add-ons and extensions that must be signed for installation.
Some extensions, such as themes, do not need to be signed. This way, the code clears the constant of all types of additions, so installing any of them does not require a signature.
The code in the second file tells Firefox to load the config.js file when it starts.
It’s strange that it’s so simple, considering that mandatory signing of extensions is used to improve security.
We are talking about multi-process Firefox 42, where an error occurs when automatic installation- incl. With
In theory, you just need to download the .xpi file and then drag it to open window add-ons, but Firefox says that
This add-on cannot be installed because it has not been verified.
People offer this solution:
about:config > xpinstall.signatures.required = false
but in my case the fox still answers:
Firefox Developer Edition blocked the installation request software to your computer from this site.
Solution
The easiest way is to add
getfirebug.com/releases/firebug/3.0/
To the list of sites to which the check is not applied, go to the address bar of the browser:
about:preferences
Select the Security section on the left and click on the exceptions button on the right and add a new address.
Now you can install directly from the site, Firefox will still throw a warning, but now you have the opportunity to agree to the installation - and voila - firebug 3 alpha (still alpha) is installed!
Add-ons stopped working in the new version of Firefox?
I recently installed updated version LastPass 4.0 on the Firefox browser, and today this extension stopped working. Along with it, several other add-ons were disabled, including Kaspersky Protection. The fact is that in Firefox 43 all add-ons must be verified by Mozilla.
This was done for safety, but everything new often creates inconvenience. How to get untrusted apps you trust to work in Firefox?
Enter in the address bar about:config
Find in search bar meaning xpinstall.signatures.required and click on this line twice. Meaning true should change to false. Now your favorite add-ons will work again.
In the latest versions of the web browser Mozilla Firefox By default, almost all plugins are disabled.
For example, instead of Adobe plugin Flash Player you can see the following message “This plugin is vulnerable and needs to be updated. Check for updates... Click here to enable the Adobe Flash plugin":
In this case, a red “cube” is displayed in the left corner of the browser’s address bar; clicking on it, you will see a message “To ensure your safety, some plugins have been disabled...”. Here you can enable all plugins for the current web page:
If you want to disable this annoying option:
– in the address bar of the browser, enter about:config, press Enter;
– in the message window “Be careful, otherwise you will lose your warranty!..” click the button I promise I'll be careful!;
– in the next window in the text field Search(located at the top) enter plugin;
Appeared relatively recently new Mozilla Firefox 43 began blocking unfinished extensions by default.
This solution was implemented by the developers in order to increase the level of browser security.
However, for most users. Who prefer Mozilla browser Firefox given I didn’t like the new product because it could cause some inconvenience. In this article you can learn how to enable extensions. mozile.
What is an extension
The extension is a small application that improves the functionality and usability of the browser. For example, you can install a program that will block annoying advertising and spam when visiting sites, or change the standard appearance of the browser to a more creative one, etc.
Add-ons are divided into three main types:
Allows you to add additional functions for a search engine, or replace them with those available in other browsers. Add-ons allow you to block ads or sites that pose a potential threat to your PC, as well as download videos from any resource or integrate with social networks.
They allow you to change the standard background of the search engine, as well as visually change the appearance or location of buttons and panels. 
Allows the user to interact with the most different types Internet content such as videos, games, music, etc.
The user can download these extensions from the mozilla search engine catalog. IN this catalog All programs are tested and checked for malware.
However, in the latest version of mozilla, even programs contained in the directory are blocked.
To install improvements you will need to use forced method. Below are several methods for forcing installation. 
Method No. 1:
- Login to Mozilla
- Enter about:config in the address bar.
- Press the button
- After the security window pops up, agree to the terms.
Method number 2:
- Go to the settings panel.
- Find xpinstall.signatures.required.
- Click LMB several times.
- After the entry changes to false, you can install the improvements.
After such manipulations, you can install in Mozilla browser Firefox 43 various add-ons that will be relevant to the user. However, in in this case Caution is recommended as such installations may pose a potential hazard.
The user should also take into account that when the next search engine update is released, all previously specified parameters will be reset.
Force installation of extensions in Mozilla Firefox
I decided to update Mozilla to beta version 7.0b4
But after the update I discovered that some extensions were disabled.
In Firefox, various extensions are tested for compatibility by developers and restrictions are set on the browser version to eliminate incompatibility and glitches.
But we, the advanced ones, need everything at once. And I can’t bear to wait until they test the next, especially beta, version of the browser. In my case, the All-In-One Sidebar extension was disabled. IMHO - too convenient an extension to wait for testing, so I decided to start testing myself!
For manual installation This extension will increase the limit on the maximum browser version. For convenience, I will break down our actions into points:
1. Let's find and download the extension itself. I downloaded it from the official website http://firefox.exxile.net/aios/index.php. As a result, I received the file “ all_in_one_sidebar-0.7.14-fx.xpi«
2. Let's unpack it. As it turned out, .xpi- this is normal zip archive with modified extension.
Change the extension to .zip and unpack it with any archiver.
3. As a result, we will get a bunch of files, we are interested in the file located at the root of the archive - “ install.rdf". Open it for editing. In it we are only interested in the section “ em:targetApplication«:
4. Save the file. We pack all previously unpacked files into ZIP archive with standard compression and change the extension back to " .xpi«.
Hello. I don’t know about you, but it’s hard for me to imagine my Internet browser without Yandex Elements. They may not be among the functions you can’t do without, but you must admit that Yandex elements make our stay on the Internet more comfortable. Visual bookmarks, quotes, fast access To social networks and mail, weather forecast, road conditions save time and make life easier.
In general, I need them, period. So - having taken up the planned reinstalling Windows 7, I downloaded fresh drivers for PC, video codecs, new versions of your favorite programs, installed Yandex.Browser and the latest Mozilla version Firefox. I immediately launched Firefox with the goal of installing Yandex Elements, but the problem was that when I went to the office. elements website and clicking on the “install” button as usual, I received a connection error and the installation was reset.
I checked the connection, tried a couple more times - Yandex elements for Mozilla Firefox are not installed, no matter what, luckily I didn’t suffer for long, I remembered how to solve this problem...
Why Yandex Elements are not installed
for Firefox and how to install.
Honestly speaking, why wasn’t the Yandex elements extension installed in Firefox in the usual way today, with the wording “the add-on could not be loaded due to a connection error with element.yandex”, I was too lazy to delve into it, because the installation method shown below worked the first time, that’s all It worked and I lost interest in the developers' graters.
So, how to bypass the error and install Yandex Elements for Mozilla Firefox. Open the official page - YandexElement , the browser should be detected automatically and you will see the words “Dialing” above the button. useful extensions for Mozilla Firefox." Right click click on the “Install” button, in the menu that opens, select “Save object as...”.
In the explorer window that opens, indicate the folder (the one that is easy for you to find, the working one that you use for downloads), remember the name of the downloaded file, Yandex elements - YandexElement.xpi. We look up, click on “Tools” in the browser menu, and click on “Add-ons” in the submenu that appears.
In the add-ons window, select “Get add-ons”, on the right in top corner we find the gear, if you hover the mouse, the hint “Tools for all add-ons” will pop up, left-click the mouse, and select “Install add-on from file” in the submenu.
In the explorer that opens, find the folder with the saved Yandex Elements for Firefox, select “YandexElement.xpi”, click open. A standard warning window will appear asking you to install add-ons from “honest authors”, with this we are all right - we downloaded the extension from official page Yashki, click “Install now”.
The inability to install an extension may be the result of problems with the extension, settings, or version of Firefox you are using. This article describes the various causes of installation problems and what you can do to resolve them.
Add-ons are not compatible
A file located inside each add-on specifies the range of Firefox versions with which the extension is compatible. In the Firefox Mozilla Add-ons section, you can view information about compatible versions on the page available for each extension.
If the version of Firefox you have installed is not within this range, installing this add-on will result in an error indicating that the add-on is not compatible. If your version of Firefox is not compatible with the add-on, you can:
- Update to the latest version of Firefox. For getting additional information Read the article Updating Firefox to the latest version.
- Find versions of this add-on that are compatible with your Firefox version. The Firefox Add-ons website typically contains the most latest version each addition.
- Use a different extension. For many extensions, there are similar extensions that perform the same functions. For more information, please visit the Firefox Add-ons website.
Firefox has blocked the installation of an unverified add-on from this site
The add-on cannot be installed because there is a high risk of instability or security problems.
Firefox rejected a site's request to install software
By default, Firefox only allows you to install add-ons from trusted websites. If the site from which you install add-ons is not in the list of trusted websites, a yellow bar appears at the top of the web page with a message similar to the following:
Firefox has blocked a request to install software on your computer from this site (www.example.com).
To allow the site, click Allow in the yellow bar.
To add a site to the list of trusted sites:
You are asked to download the add-on, not install it
Some websites provide add-ons as downloadable files, requiring you to download the file to your computer before installing it.
- These files usually have the extension .xpi or .jar.
Load Error -228
Cache disabled
This error message may be caused by Firefox cache disabled. For restart Firefox cache:
Other programs
Sometimes firewalls or anti-spyware screens can result in a Boot Error -228 message. If you are using firewall C.A. Windows Defender or the resident setup of Spybot S&D (the "TeaTimer" feature), you will need to temporarily disable this software to verify that your system allows the installation of add-ons. For more information, refer to the documentation included with the software.
Nothing happens when I click the installation link
Extension configuration files are corrupted
Corrupt extension configuration files can cause problems when you try to install an extension. Deleting these files will allow Firefox to recreate them (removing any corruption) the next time you launch it. You will not lose your extensions or their settings when you delete these files.