Firefox bug - Unrecognized storage name 'null' in about:cache URL
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.