You can possibly achieve this by using a policies.json file via the ExtensionSettings policy. You can also use it to block access to about:config (BlockAboutConfig) and prevent Safe Mode (DisableSafeMode).

• https://support.mozilla.org/en-US/kb/customizing-firefox-using-policiesjson
• https://github.com/mozilla/policy-templates/blob/master/README.md

I have added: gpedit.msc I try add options "Lock" for Kaspersky Protection. But I don't know how can I correctly create list extension...? When I tryed write "Kaspersky Protection" or "ID Extension" nothing do. Extension is not locked.

What I do wrong?

As shown under https://github.com/mozilla/policy-templates/blob/master/README.md#extensionsettings

To obtain an extension ID, install the extension and go to about:support. You will see the ID in the Extensions section.

I did file: "policies.json" and created folder "distribution" in: C:\Program Files\Mozilla Firefox

For KASPERSKY: policies.json has: {

 "policies": {
   "Extensions": {
     "Locked":  ["light_plugin_7571494CE0B94E11BB762B659A4AD71F@kaspersky.com"]
   }
 }

} Work correcty :-)

But someone can show me how correctly add content: {

 "policies": {
   "DNSOverHTTPS": {
     "Enabled":  true,
     "Locked": true,
   }
 }

} I can't do creat corectly file structure :-( *.json.

The problem was resolved :-)

{

 "policies": {
   "DisablePocket": true,
   "Extensions": {
     "Locked":  ["light_plugin_7571494CE0B94E11BB762B659A4AD71F@kaspersky.com"]
   },
   "DNSOverHTTPS": {
     "Enabled":  true,
     "Locked": true
   }
 }

}

If You want block extension You need, "@mail" you can use... about:support And next You have table: Extensions, which include ID Extension "@mail".

Hi

You forgot to remove the trailing comma in "Locked": true, A comma is only mandatory as a separator and there shouldn't be a comma before a '}'

You also need only one policies section, so you need to add the other rules under the main policies section and separate each rule with a comma.

{
 "policies": {
   "Extensions": {
     "Locked":  ["light_plugin_7571494CE0B94E11BB762B659A4AD71F@kaspersky.com"]
   },
   "DNSOverHTTPS": {
     "Enabled":  true,
     "Locked": true
   }
 }
}