If you have a book that is in our old Google Docs writing mode (which we no longer support, for reasons we set out here), we recommend the following:
1. Switch to another writing mode. Here is an article about switching writing modes, which just takes a click or two.
If you want to write your book using a Leanpub writing workflow, we suggest you choose the "In my browser with a Markua plain text editor" mode.
You can find walkthroughs for all our writing modes here.
2. If you'd like to keep writing in Google Docs, then we suggest you switch to the Upload writing mode in Leanpub. Then, whenever you would like publish a new version of your book on Leanpub, you can export a PDF from Google Docs, and upload that for sale on Leanpub.
3. Or, of course it may be that Leanpub is not the best solution for you! If that is the case, we wish you all the best with your book project as you find another platform or workflow.
We're sorry this all wasn't communicated better. If you're interested, we wrote a long essay about some changes we made here: https://leanpub.com/simplifying.