Whispersync is one of my favourite Amazon features.
You can read a book across multiple devices and synchronize your place as you read. Amazon has enabled Whispersync even for ‘personal documents,’ aka books you didn’t buy from them. That’s handy! But it’s glitchy. Lately, I have found that some of my books are not synchronizing.
I tried a few quick solutions. I deleted the book and re-downloaded it. I forced a sync with the manual ‘sync’ button. Nope. I resigned myself to restricting certain books to only the device where I first started reading them. But I was frustrated. I wanted this feature to work!
A Reddit thread finally gave me the answer: Amazon doesn’t care if you bought their book. But they do care if you have their metadata. Your file needs to be encoded with Amazon’s book ID in order for the sync to work properly.
This was where I had made my mistake! For most of my books, I load them into Calibre and give them a quick check. If the cover art looks ok and a summary is already there, I don’t go any further. I convert the usually-ePub file to Mobi and use the send-to-Kindle app.
Conversely, if the cover art is missing or there is no summary, I use Calibre’s download metadata button to fix it. And, among other things, this feature downloads Amazon’s metadata while it’s doing its thing. These books all sync just fine.
The moral of the story? Frequent side-loaders should run their non-Amazon purchases through Calibre first. It’s not just that this fantastic—and free—app can help you track and catalogue your books. But it can also keep your side-loaded books synchronizing smoothly.
Ideally Amazon can fix the glitch making the Calibre-based fix necessary. Some people, of course, might say it isn’t a glitch at all. But I myself don’t think the metadata should need to be present in personal documents for Whispersync to work reliably.