It seems the error maybe related to a page (‘Home Test’) that I have marked as ‘Do Not Publish’:
I have managed to individually publish all the other pages but not this one (which makes sense). The only downer on this investigation was that I was working my way publishing the individual pages from the bottom of my list of 28 pages, to the top, so it took a bit of time to discover this as the problem page as it was was number two in the list!
When I flipped it to publish then my Publish All worked for the whole site.
If I try and individually publish the page marked as ‘Do Not Publish’, I get the error as originally reported.
I suspect this has happened since version 1.0.9?
UPDATE
I can replicate this issue using the North Eleven website downloaded from the Marketplace. The error occurs if I select the Portfolio page not to publish.