title_body: How to debug GPB "This file cannot be processed." I tried uploading several books from Project Gutenberg and I'm getting errors on a few stating in red that "This file cannot be processed".
  
  I click on the learn more link but it doesn't really connect me to anything debug worthy.
  
  
  Anybody know how to get information about what exactly went awry?
upvoted_answer: So I solved this issue by converting epub file to mobi format (mobi is the format kindle uses) and then converting back to epub. After doing this, google books didn't have issues processing it. There are multiple online converters you can use.