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Security Exceptions

  • 5 replies
  • 1 has this problem
  • Last reply by cor-el

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We need to use a 32 bit Firefox ESR 38.5.1 because of an outdated crucial app in our organizaton

We are in the process of upgrading from Windows7 to Windows10 and now the policies.js file, located in "c:\program files (x86)\Mozilla Firefox\defaults\pref" does not work on the windows 10 computers.

We need to add a couple of url:// security exceptions to all Firefox browsers on these new machines and Icannot find what config file has these exceptions.

Can you tell me where there security exceptions are written to in windows 10 so that we can deploy them as part of the installation?

All Replies (5)

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Usually a whatever.js file in --

C:\Program Files (x86)\Mozilla Firefox\defaults\pref

-- will point to a second file, located in the program folder --

C:\Program Files (x86)\Mozilla Firefox

-- often named mozilla.cfg.

Is the problem that your pref() or lockPref() commands in mozilla.cfg (or whatever your file is called) are not working?


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Both files are there, but the add on sites, do not load in the options, security, exceptions window. After you copied over the policies.js file you would see the exceptions in the list.


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Hi Kat, I can't think of any reason for the files to work differently on Windows 7 and Windows 10.

What is the code you are using to give sites permission to install extensions? As far as I know, the "install" permissions end up being saved in a SQLite database named permissions.sqlite in the user's profile folder. Of course, I can't check Firefox 38.

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

/* Add-on Installation allowed sites */ {

 "policies": {
   "InstallAddonsPermission": {
     "Allow": ["",
     "Default": [true], /* If this is set to false, add-ons cannot be installed by the user */


Here is the script that is in the default/pref folder.


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A policies.json file with policies in JSON format like you posted needs to be in the distribution folder. The two pref lines do not have to be in the policies.json file.

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

The autoconfig file with the file name set via a .js file in the defaults/pref folder that can store pref() calls to set or lock prefs needs to be in the main Firefox program folder where the .exe file is located.

About policies, see also: