Opening `about:cache` does not show any entries. The reason seems to be that `Private` is unchecked. Doing that and trying to update the cache is resulting in an error: ``` Unrecognized storage name 'null' in about:cache URL ``` This is actually a Mozilla bug as this happens in a vanilla Firefox as well. But now clicking on `Back to overview` does give us the cache entries as `Private` is checked.