Google Play Books Processing Failed

When you’ve got ‘the processing failed’ message. You just need to follow these simple steps:

1. Download Calibre (https://calibre-ebook.com/download_windows64).
2. Add your epub to the calibre and convert it to mobi file format.
3. Re-convert your mobi to epub.
4. Then try to upload your new epub to the google play books.

I hope these instructions can solve your problem, cheers!