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KDP upload errors, explained

“There was an error processing your file” tells you nothing. Here’s what KDP is actually objecting to, error by error, and the fix for each — from the pipeline that has debugged all of them.

“There was an error processing your interior file”

Why it happens: KDP's converter choked before it could even review the layout. Usual suspects: a corrupted .docx (often after cloud-sync conflicts), unsupported elements (embedded video, macros, form fields), a PDF produced by a broken exporter, or a file saved in an old format.

The fix: Re-export a fresh copy: in Word use Save As → .docx (not 'compatibility mode'), or export a new PDF with fonts embedded. Strip comments, tracked changes, and content controls. If it still fails, print-to-PDF as a last resort — it flattens whatever the converter hates.

Cover dimensions don't match the interior

Why it happens: The single most common print rejection. Your cover PDF was built for a different page count, paper type, or trim than the interior you uploaded — even a few pages' difference changes the required spine width.

The fix: Rebuild the cover using your final page count and paper choice. Our cover size calculator gives the exact full-wrap dimensions, and the template generator produces a guide file at those dimensions. Any interior change → recheck the cover.

“Text/images outside the printable area” or margin violations

Why it happens: Content sits closer to the page edge than KDP allows: inside margins thinner than the required gutter for your page count, or outside margins under 0.25″ (no bleed) / 0.375″ (with bleed).

The fix: Set mirrored margins with the correct gutter — it scales with page count (0.375″ up to 150 pages, up to 0.875″ at 700+). Our margins cheat sheet has the full table. In Word: Layout → Margins → Custom → Mirror margins.

Fonts not embedded

Why it happens: Your PDF references fonts instead of embedding them, so KDP can't guarantee the printed output matches what you see.

The fix: In Word: File → Options → Save → 'Embed fonts in the file' before exporting. In InDesign/Affinity: export as PDF/X-1a or PDF/X-3, which forces embedding. Avoid fonts whose license blocks embedding — the exporter will silently skip them.

Low-resolution image warnings

Why it happens: Images under 300 DPI at printed size. A photo that looks fine on screen at 72 DPI prints soft and triggers the previewer's yellow warnings.

The fix: Insert images at full resolution and never enlarge them past 100%. For covers: the full-wrap file needs to be 300 DPI at final size — a 1600px-wide image stretched across a 13″ cover is ~123 DPI and will look it. Warnings (yellow) let you proceed; errors (red) block publishing.

Page count out of range

Why it happens: Your file converts to fewer than 24 pages (paperback minimum) or more than the cap for your ink/paper (828 for black ink, 600 standard color, 550 hardcover).

The fix: Too short: add front/back matter or increase trim-appropriate font size legitimately. Too long: move to a larger trim (5×8 → 6×9 cuts roughly a quarter of pages), tighten spacing, or split into volumes.

Bleed set wrong

Why it happens: Interior formatted with bleed but uploaded as 'no bleed' (or vice versa), or the page size doesn't match the with-bleed dimensions (trim width + 0.125″, height + 0.25″).

The fix: Text-only books: choose no bleed, page size = exact trim size. Full-page images: choose bleed and set the page size to the with-bleed dimensions from our trim size chart.

EPUB validation failures (ebooks)

Why it happens: Malformed EPUB internals — broken links in the TOC, missing cover metadata, invalid XHTML.

The fix: Run your file through epubcheck and fix what it reports; our epubcheck error guide translates every common code. Or upload a .docx and let KDP convert — it's more forgiving than a hand-built EPUB.

Or upload files that pass the first time.

publish.ai generates KDP-ready files from your manuscript — validated EPUB, interior PDF with correct margins and gutter, cover wrap at exact spine width, all at 300 DPI. The errors on this page are the ones our pipeline exists to prevent.

Publish my book →Browse a real sample package

Common questions

Why does KDP say 'error processing your interior file'?＋

The converter failed before layout review — usually a corrupted or old-format .docx, unsupported embedded content (video, macros, form fields), or a malformed PDF. Re-exporting a clean .docx or a fonts-embedded PDF fixes the vast majority of cases.

Why was my KDP cover rejected for wrong dimensions?＋

Nearly always: the spine width was computed for a different page count or paper type than your final interior, or the file was exported at trim size instead of full-wrap size with bleed. Rebuild the cover from your final page count.

How long does KDP review take after a successful upload?＋

Publishing review typically takes up to 72 hours (often much less). If your book bounces back with errors, fixing and resubmitting restarts the clock, which is why catching problems in the Previewer first saves days.

Are yellow warnings in the Print Previewer a problem?＋

Yellow warnings (like low-resolution images) let you publish anyway — they're telling you quality may suffer. Red errors block publishing until fixed. Treat yellows seriously for covers; readers notice soft cover art.