This guide is not a substitute for Amazon KDP’s own technical requirements, which can change. It is a practical explanation of the problems we see most often when an author has a manuscript or cover that will not pass review.
1. The PDF page size does not match the trim size.
Trim size is the final size of the printed book. The interior PDF has to be built for that size. If the book is 6 x 9, the PDF cannot quietly be letter-sized, A4, or some custom document that only looks correct on screen.
If the book uses bleed, the PDF page size changes again. A common mistake is selecting a trim size in KDP while uploading a file built to a different physical size.
2. Bleed was used incorrectly—or not used when it was needed.
Bleed is needed when images, backgrounds, rules, or other visual elements run to the edge of the page. Text-only novels usually do not need interior bleed. Illustrated books, maps, art books, full-page chapter ornaments, and pages with background color often do.
The problem is not only whether bleed is selected. The file itself must be built to the correct bleed dimensions, and the art must extend past the trim line far enough to avoid a white sliver after cutting.
3. Text or important images are too close to the edge.
KDP may warn when live text, page numbers, running heads, or important images sit too close to the trim area. Even if the previewer lets something pass, print trimming is not perfectly microscopic. A file can look acceptable on screen and still be risky as a physical book.
This is especially common on back covers, illustrated interiors, chapter openers, and books where the author tried to use every bit of space to reduce page count.
4. The gutter margin is too narrow.
The gutter is the inner margin near the binding. The thicker the book, the more room the gutter needs. A 90-page paperback and a 500-page paperback cannot use the same inside margin and remain equally readable.
If the gutter is too small, the book may pass upload but become uncomfortable to read, with text disappearing into the binding.
5. The cover was built from the wrong page count or paper choice.
Full-wrap covers depend on trim size, page count, ink, paper type, and format. Change the page count after formatting the interior and the spine width may change. Change paper type and the spine may change again.
This is why a cover that once fit can suddenly fail after one more interior revision. The cover and interior have to be finalized together.
6. Text falls into the barcode, trim, fold, or hinge area.
Paperback and hardback covers have safe zones. Back cover copy, author photos, logos, prices, decorative rules, and imprint marks need to stay clear of trim lines, fold lines, barcode areas, and hardback hinge areas.
A common failure is a cover that looks visually balanced as art but ignores the mechanical zones of the printed object.
7. Fonts are not embedded or the PDF was exported badly.
A print-ready PDF is not just a file that opens on your computer. Fonts should be embedded, transparency and images should behave predictably, and the export settings should preserve the layout as intended.
Problems often appear when a file has been passed between Word, Canva, Affinity, PowerPoint, Google Docs, Acrobat, or online converters without a controlled export process.
8. Images are too small, stretched, or unsuitable for print.
Images that look good on a phone can print poorly. Covers and illustrated interiors need adequate resolution at the size they will actually print. Stretching a small image across a full cover or a full page usually creates softness, blur, or visible artifacts.
Image problems are also common when screenshots, social-media images, low-resolution downloads, or heavily compressed files are placed into a print layout.
9. The book was formatted visually instead of structurally.
Some files are built by dragging text boxes and images around until the pages look right. That can work for a poster or a single flyer. It becomes fragile in a book, especially when front matter changes, chapters move, images cross margins, or the page count shifts.
A stable book file needs consistent styles, predictable spacing, correct page setup, and deliberate export settings.
When it is worth asking for help
If the same file has been rejected more than once, or if fixing one warning creates another, the problem is usually structural. At that point, a targeted repair may be faster than guessing through repeated uploads.
What to send if you need a diagnosis
- The exact error message or screenshot from KDP.
- The rejected interior PDF and/or cover PDF.
- The book’s trim size, paper type, format, ink choice, and page count.
- The KDP cover template or the settings used to calculate the cover.
- A note explaining whether this is paperback, hardcover, ebook, or more than one format.
A clean diagnosis is often the difference between a small production correction and a full rebuild. The goal is not to make the process mysterious. The goal is to make the book file behave like the physical book it is supposed to become.