You fixed the chapter. Amazon won't send it to the people who already bought the book.

A reader emails to say chapter seven has the wrong figure in it. You check, they're right, you fix it, and you upload the corrected file to KDP that evening. Done.

Except it's done for the next person who buys the book. The reader who told you about the mistake still has the version with the mistake in it, and so does everyone else who bought before Tuesday.

What KDP actually does with a new file

When you publish a revised manuscript, Amazon serves it to new buyers. Getting it to people who already own the book is a separate request, and KDP's own help page is clear about how narrow that request is.

Updates go to existing customers only for "critical quality issues that significantly affect readability." You have to ask, with the ASIN, detailed examples of each correction and the Kindle location of each one. Then KDP lists what it won't send, which is worth reading slowly:

• added, deleted or changed words, sentences, pages, chapters or images
• changed character names or plot
• added, deleted or changed links or marketing information
• changes big enough to count as a new edition

Typos that make a page unreadable, broken formatting, a missing chapter: those qualify. A rewritten section doesn't. Neither does the thing most authors actually want to change, which is the back matter.

And even an approved update isn't guaranteed to land. It arrives when the reader closes the book, can take days, and readers who've switched automatic book updates off have to go and fetch it from Manage Your Content and Devices themselves. Most of them won't know there's anything to fetch. KDP's page also warns that sending updated content may wipe a reader's notes, bookmarks or highlights, which is part of why the bar is set so high.

The updates this rules out

Read the refusal list again with a specific book in mind.

Non-fiction goes out of date. A book about tax, software, a medical condition or a regulation is correct on the day it's published and slowly less correct after that. The fix is a revised chapter, and a revised chapter is "changed sentences, pages, chapters". The readers who most need the update, the ones who bought early and trusted it, are the ones who don't get it.

Technical books are built to be revised. A programming book with an API that changed six months after launch needs a new code sample, not a typo fix.

Series back matter is marketing, by definition. The last page of book one should point at book two. When book two comes out, the readers who bought book one at launch, your most committed readers, are holding a copy that says "coming soon" with no link. Updating that page is "added links or marketing information". It's refused.

None of this is unreasonable from Amazon's side. It's moving millions of files onto devices it has to support, and an update that wipes someone's highlights is a support ticket. But it means your book on Amazon is effectively frozen for everyone who already bought it.

What it looks like when the file is yours to serve

When you sell direct, the buyer doesn't get a copy pushed onto a device by a third party. They get a link, and the link is yours.

On Inkwharf, every buyer gets a permanent download page. It doesn't hold a copy of the file they bought; it serves the book's current file. Upload a corrected EPUB and every past buyer's page serves the new one from that moment. There's no review, no request with Kindle location numbers, and no category of change that doesn't qualify. A new chapter, a fixed diagram and a back-matter link to book two all go out the same way.

Each upload is kept as an edition, with an optional note on what changed, and the download page shows that note to anyone who already bought. Then it's your call whether to email them about it. The notice goes out once per edition, only to people who own the book, and only when you send it. Nothing mails your readers automatically.

Two honest limits:

• A file someone already downloaded doesn't change. If a reader saved the EPUB to their laptop, that copy is the old one until they download it again. The edition notice exists so they know to.
• Send-to-Kindle copies are personal documents. A buyer who sent the book to their Kindle has a copy Amazon treats as theirs, and it won't update itself. Sending it again from the download page replaces it. How the book gets to a Kindle in the first place covers the rest of that path.

Sell in both places, and know which copy is current

None of this means leaving Amazon. Most authors who sell direct keep the book on every retailer, and there's no exclusivity either way unless you've signed up for one. What changes is which of your readers can get the corrected book.

If you revise often, the people who buy from your own shop are the only readers guaranteed the current edition. That's worth saying out loud on your sales page, especially for non-fiction: buy here and you get every update. It's a real reason to buy direct, and it's not one a retailer can match.

For the other reasons that tip a reader toward your shop, and the ones that don't, direct sales versus the retailers does the arithmetic without the cheerleading.

Open a shop: one download link per buyer, and every edition you upload reaches all of them.