Not working in Firefox, when Autoplay is set to Block, and the site has an exception.

[ziroc]

The error is Uncaught (in promise) DOMException: The play method is not allowed by the user agent or the platform in the current context, possibly because the user denied permission.

[ken107]

If you disable autoplay, the scripts cannot play audio programmatically

[ziroc]

Well, I disable it for a reason. And I expect that it will work on sites that I have made exception for.

[adrian91221]

Try setting media.autoplay.blocking_policy to 0 or 1 in about:config. Autoplay will be blocked but the extension will work properly.