What this error means
KDP's metadata reviewer runs an OCR pass over your interior PDF, finds the ISBN-13 string on the copyright page, and compares it to the ISBN you entered in your KDP dashboard. If they don't match, the rejection email reads "Metadata mismatch: the ISBN in your manuscript does not match the ISBN you have entered."
It's strict. A space in the wrong place, a single transposed digit, or printing your old ISBN on a second edition all trigger it. KDP also catches the reverse case: you forgot to print the ISBN at all and entered one in the dashboard.
This rule applies whether you're using a free KDP-assigned ISBN or a paid Nielsen UK ISBN. Both must match what's printed.
Why it happens
The most common cause is using a template copyright page. Vellum, Atticus, and Word templates ship with placeholder text like "ISBN: 978-X-XXXXX-XXX-X" — authors forget to replace it with their real number.
Updating one place but not the other. You buy a new ISBN from Nielsen, paste it into the dashboard, but never update the copyright page in your manuscript. Or vice versa.
Second editions are a frequent trip-up. You re-use last year's manuscript, change the cover, but the old ISBN is still in the back. KDP requires a new ISBN for any new edition.
Multiple formats with shared interior. If you re-use the paperback interior for the hardcover but only have a paperback ISBN printed, KDP rejects the hardcover. Each format needs its own ISBN.
Hyphen confusion. ISBN-13 can be written as 9781234567890 or 978-1-234-56789-0. KDP normalises both, but if you enter one variant in the dashboard and print a clearly malformed version (e.g. 978-12-3456-789-0), the OCR can read it as a different number.
The fix
Step 1: Open your KDP dashboard. Note the exact ISBN-13 you've registered for this edition. Copy it.
Step 2: Open your manuscript and find the copyright page. It's usually page 4 of the front matter.
Step 3: Update the printed ISBN to match the dashboard. Standard UK format is:
ISBN (paperback): 978-1-XXXXXX-XX-X
ISBN (hardcover): 978-1-XXXXXX-XX-X
ISBN (ebook): 978-1-XXXXXX-XX-X
If only one format is being published right now, only print that ISBN. Don't list ISBNs for formats you haven't published yet.
Step 4 (Word): Find and Replace (Ctrl+H) on the old number. Save. Re-export to PDF using Save As → PDF → Standard.
Step 5 (Vellum): Click Settings (cog icon) → Title Page → Copyright. Update the ISBN field. The change propagates automatically to the rendered output.
Step 6 (Atticus): Project → Front Matter → Copyright Page. Update ISBN. Generate → re-export PDF.
Step 7: If you're using a KDP-assigned free ISBN, you generate it after uploading. So upload your manuscript first, then come back, copy the assigned ISBN, paste it into the copyright page, and re-upload. KDP allows this two-step process.
Step 8: For UK authors using Nielsen ISBNs, you can buy single (£89) or block of 10 (£164) from nielsenisbnstore.com. Block is the better deal if you publish more than once.
Step 9: After fixing, re-upload the corrected PDF and re-save the metadata. Both halves trigger re-validation.
How to pre-flight it
Our free KDP Readiness Score extracts every ISBN-shaped string from your PDF and lets you visually confirm it matches what you'll enter in the dashboard. The audit covers 30+ other KDP rules so you ship a clean file in one upload.
Related errors
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- KDP error: AI content not disclosed
- KDP error: cover trim doesn't match interior
FAQ
Do I need an ISBN for KDP at all? No — KDP will assign a free ISBN-equivalent (an ASIN) for ebooks and a free ISBN for print. UK authors who want their book in Nielsen BookData / WHSmith / Waterstones need a paid Nielsen ISBN.
Can I re-use my paperback ISBN for the hardcover? No. Each format must have its own ISBN. Same content, different binding = different ISBN.
What about ebook ISBNs — does Kindle need one? KDP doesn't require an ISBN for Kindle ebooks (it issues an ASIN). But if you list elsewhere (Apple, Kobo, libraries) you'll need one.
My ISBN has hyphens, the dashboard's doesn't — is that the mismatch? No — KDP normalises hyphens. Mismatches are always actual digit differences. Triple-check character by character.
