Created 1.7 Extension Exceptions (markdown)

1.7-Extension-Exceptions.md

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+Cookies control access to **local storage** and **indexedDB**. The `ghacks user.js` denies cookies by default. This is the pref `network.cookie.cookieBehavior` (2701). A value of `2` denies all cookies, a value of `1` allows first party only.
+
+Extensions <sup>1</sup> that use local dom storage and/or indexedDB **will break** if they are not allowed a cookie, even though they do not actually set any. Extensions that use such storage include uBlock Origin, uMatrix, Stylus and Violentmonkey.
+
+You have two choices
+ - Allow first party cookies and use an extension to clean up and/or block cookies and storage
+ - Deny all cookies and use site exceptions, **including** exceptions for extensions that need it. And you can still use an extension to clean up and control those cookies and storage if you want.
+
+<sup>1</sup> `Extensions` = Web Extensions API, `Legacy Extensions` = legacy APIs or the Add-on SDK.
+
+:small_orange_diamond: How To Set Extension Cookie Exceptions
+
+- Open `about:debugging > Add-ons`
+- Click on the `Manifest URL` of the extension
+- On the manifest page, right click and select `View Page Info`
+- Select the `Permissions` tab
+- For `Set Cookies`, uncheck `use default` and check `Allow`
+- Restart Firefox for the extension to start using storage
+
+You can view cookie exceptions under Options > Privacy & Security > History > custom settings > Accept cookies from websites > Exceptions
+
+:small_orange_diamond: Note
+- The exception uses the extension's `UUID`, which is a random unique value generated on each install of the extension.
+- If you are cleaning cookies via a third party appllication, such as CCleaner, make sure to keep these cookies
+