I'm using Firefox Developer Edition v79, and I've been getting plagued by a particular issue for a while, but only recently found a bug report that clued me into the cause - and it's specific to the portable version only.
Preface:
Firefox prohibits extensions from working on their own site (specifically, addons.mozilla.org). In order to allow extensions to work on this protected site, you have to do the following in about:config:
- Clear the contents of "extensions.webextensions.restrictedDomains".
- Create/Set "privacy.resistFingerprinting.block_mozAddonManager" to True.
Problem:
However, it turns out that there is a problem - when "privacy.resistFingerprinting.block_mozAddonManager" is set to True, you can't install addons from addons.mozilla.com. They fail with the error "The add-on could not be downloaded because of a connection failure."
You can still manually save the XPI file and install it by pointing the URL bar to the local path - but direct installs from Mozilla's site will not work.
But here's the real issue - this problem ONLY exists in the portable version. In the normal installed version, setting "privacy.resistFingerprinting.block_mozAddonManager" to True doesn't cause the problem with installing extensions.
Is this something that is fixable?