Free EPUB Validator for KDP Upload Errors and EPUBCheck<br>Skip to main content

Free EPUB validator and repair for KDP upload errors and EPUBCheck failures.<br>Upload the exact .epub to check for errors. The report names affected paths, separates checked EPUB repairs from manual work, and only shows a download after EPUBCheck passes again.<br>KDP upload errors/Kindle Previewer messages/EPUBCheck codes/Apple Books or distributor rejection<br>Upload EPUB to scan

Example scan report<br>3 upload blockers found

Second EPUBCheck<br>Passed

Repairable

Manual review

Download<br>Ready

RSC_007Missing image targetManual review<br>OPF_030Unique identifierRepairable<br>PKG_006Mimetype orderRepairable

EPUBCheck passed againRepaired EPUB available

Use the upload when the EPUB itself failed KDP, Kindle Previewer, or EPUBCheck. EPUB Fixer follows the package paths in that file, stops before changing book decisions, and only shows a repaired download after another EPUBCheck pass.<br>Uses the file you retry<br>Upload the exported .epub that failed. The scan follows package files, links, anchors, and metadata inside that exact file.

Names the failing path<br>The report points to the OPF, nav.xhtml, chapter, image, stylesheet, anchor, or manifest entry behind the upload blocker.

Stops before guessing<br>If the next move depends on reading order, headings, images, or layout, the report stops at manual review.

Checks again before download<br>A repaired EPUB appears only after the written structure change passes another EPUBCheck run.

Preview a sample reportFind my EPUBCheck error

Start here<br>Choose based on what you have right now.<br>You do not need to know the EPUB internals first. Start from the file, the error text, or the sample report.

01I have the EPUB file

Upload the file you plan to check or retry.<br>Use this before KDP upload or after KDP, Kindle Previewer, or EPUBCheck rejects the exported .epub.<br>Upload EPUB to scan

02I only have the error text

Find the closest error guide first.<br>Use this when you have RSC_007, RSC_012, OPF_030, PKG_006, or a Kindle Previewer message.<br>Find my EPUBCheck error

03I want to see the output

Preview the report before using your file.<br>Use this to see affected paths, repair status, and download boundaries before uploading.<br>Preview sample report

Checked repair proof<br>A repaired EPUB appears only after the second EPUBCheck pass.<br>If that second check does not pass, the report still explains the problem, but no repaired download appears.

Detect the failing package part<br>The scan names the package path, manifest entry, anchor, or identifier behind the upload blocker before you edit anything.

Write only clear structure changes<br>Checked repairs stay inside package wiring such as manifest entries, media types, identifiers, navigation links, or ZIP structure.

Hold the download until EPUBCheck passes again<br>If the second EPUBCheck run still reports issues, the report stays in explanation mode and no checked download appears.

EPUB 3.3 package structure<br>An EPUB includes chapter files, metadata, a file list, reading order, navigation files, and a ZIP container. These parts must line up for upload checks to pass.<br>EPUBCheck conformance checking<br>EPUBCheck reports rule errors. EPUB Fixer uses those messages to separate simple fixes from issues that need a person to decide.<br>KDP EPUB upload expectations<br>KDP accepts EPUB files that meet Kindle Publishing Guidelines and recommends checking them in Kindle Previewer first. EPUB Fixer is for errors found in that step.

Coverage matrix<br>See what this scanner can repair, what it will only explain, and what it will reject.<br>This is not a general-purpose EPUB service. It only writes changes when the correct structure fix is clear and verifiable.

Can repair<br>Manifest entries or media types when the correct file already exists<br>Package identifier wiring such as OPF unique-identifier links<br>Navigation or NCX wiring when one clear target already exists<br>OPF cover metadata or EPUB 3 cover-image property when one existing cover image is clear<br>ZIP package issues such as mimetype order when the correct fix is clear

Needs manual review<br>Broken anchors when several headings or notes could be the intended target<br>Reading-order or TOC fixes that depend on author intent<br>Missing files, damaged images, cover image asset warnings, or malformed chapter content<br>Cases where the scanner can explain the problem but should not choose the fix

Out of scope<br>DOCX, PDF, KPF, or KCB conversion<br>Fixed-layout, comics, DRM-protected, or image-first EPUBs<br>Cover design, crop, upscaling, compression, redraw, KDP marketing cover, paperback PDF, spine, bleed, or barcode checks<br>Book formatting, layout redesign, or prose changes<br>KDP account, listing, pricing, tax, or review workflow issues

Common KDP blockers<br>Match the exact EPUBCheck or KDP error text.<br>Paste the code or compare the message. Most EPUB errors point to a missing file, broken link, bad metadata entry, or packaging problem.

RSC_005duplicate ID in XHTML<br>Use this when EPUBCheck...