conversion of zip and rar was never supported by calibre. What normally happens is when you add a zip file with an ebook inside it like a file in epub/lit/mobi/whatever format calirbe detects that file and extracts it. Then when you convert it is that file being converted.
Similarly, if you convert a zip or rar file directly, calibre again looks for an ebook file inside it and converts that. If no ebook file is found you get the error message you quoted.
|