Out of the box configuration works perfectly on my machine, no problems at all.
But when I deploy to our test environment - I get the following message
The accepted answer should be the first thing you try.
However, I have my XML output set to go to App_Data\ and have my Swashbuckle configured to read from that directory, so, it doesn't matter which way it gets built: the xml files are going to 'be there'. Nevertheless, I was still getting the error...
I found over at MSDN's forums @enough2012's answer:
select "Remove additional files at destination" in the "File Publish Options" within the "Settings" pane of the Publish dialog.
Worked like a charm!