EPUB FixerKDP upload error scanner

EPUB error guide

Validate EPUB before KDP upload

Upload the finished reflowable EPUB before KDP sees it, then check for EPUBCheck, Kindle Previewer, OPF, TOC, link, manifest, cover wiring, or ZIP blockers.

Best fit

You have the final exported EPUB.

Upload the .epub you plan to send to KDP, not the DOCX, PDF, KPF, KCB, or source project.

Report shows

Upload blockers by EPUB path.

The scan names OPF, nav.xhtml, chapter, image, stylesheet, anchor, manifest, container, or ZIP paths that can block validation.

Stop when

The issue is publishing workflow.

Cover upload, pricing, categories, account review, content policy, paperback files, and final KDP review are outside this structure check.

Scan EPUB structureSee an example report

Scan when the message does not name the affected path. The report shows affected paths and repair decisions, not manuscript text.

No signup before the scan report.Checks EPUB package paths, not manuscript text.Repair download only after EPUBCheck passes again.

Need fixed-layout, DRM, or source-file help? Check unsupported or review-first EPUB cases.

Match these report titles

  • Validate EPUB before KDP upload
  • How to validate EPUB before uploading to KDP
  • KDP pre-upload EPUB check
  • Check EPUB before KDP upload
  • EPUBCheck and Kindle Previewer blockers before upload
  • OPF, TOC, link, cover, manifest, or ZIP issue before KDP

Use this guide when

Your message matches "Validate EPUB before KDP upload" or one of the report titles above.

Upload if

You have the exported reflowable .epub and need the affected path, file, field, or repair decision before editing.

Handle outside this tool

Use the source tool or publishing workflow for DOCX, PDF, KPF, KCB, fixed-layout, comics, image-first books, DRM, visual design, or KDP listing and approval problems.

Read the scan report

Decide if this report item matches.

Use the report label, affected file, and repair decision together. A matching title alone is not enough if the file path or EPUB structure points to a different problem.

Error textAffected pathDecisionRepair, review, or stop

A useful report does not stop at the error name. It connects the message to an internal file and a next action.

Match the report title.

Look for "Validate EPUB before KDP upload" or the closest title above. Keep the original EPUBCheck, KDP, or Kindle Previewer wording if it differs.

Check the affected file first.

Use the Affected area, Source file, Target file, or Problem type rows before editing OPF, nav, XHTML, CSS, or image paths.

Follow the repair decision.

Repairable means one clear structural change. Needs review or Not supported means use the named file, source project, or platform step.

Keep with your repair note.

Copy these fields from the report instead of rebuilding the fix from memory.

Source file
Target path or field
Original error
Repair decision
Next step

1. Example report output

What a KDP pre-upload report should show.

A useful pre-upload report should tell you what would block validation and whether the fix belongs in this EPUB or back in the source tool.

File checked

The exported reflowable .epub that will be uploaded to KDP.

Validation layer

EPUBCheck, Kindle Previewer style structure, OPF metadata, nav.xhtml, toc.ncx, links, manifest, cover wiring, container.xml, or ZIP wrapper.

Affected path

The internal EPUB file or package entry to inspect before another KDP upload.

Decision

Checked repair, manual review, no current blocker found, or unsupported by this scanner.

Retry boundary

A repaired EPUB is offered only after EPUBCheck passes again. KDP still runs its own upload and review checks.

The report is useful when it changes your next action: upload, repair one clear structure issue, review a named path, or return to the source workflow.

2. Next step

Choose upload, repair, manual review, or source re-export.

A pre-upload check should reduce guessing before you open KDP.

Upload to KDP

No blocking structure issue is found.

Use the scan as a preflight, then still review Kindle Previewer output and KDP's own upload screen.

Checked repair

One structural issue has a clear fix.

Use this when the report can align OPF, manifest, navigation, media type, path, cover wiring, or ZIP package data and validate again.

Manual review

The right fix depends on the book.

Return to the source tool or EPUB editor when the scan points to missing content, ambiguous anchors, TOC decisions, or layout-sensitive files.

3. Concrete path example

A pre-upload scan can catch a TOC wiring blocker.

The book may open in a reader, but KDP and Previewer can still reject disconnected navigation.

Before KDP upload:
KDP file: final-export.epub
Goal: check structure before retrying upload

Report:
Primary blocker: nav.xhtml exists but content.opf does not mark it with properties="nav"
Affected path: OEBPS/content.opf
Related file: OEBPS/nav.xhtml
Decision: checked repair if nav.xhtml is the intended navigation document
Retry: download only after EPUBCheck passes again

If the EPUB has no trustworthy navigation file, rebuild the table of contents in the source tool instead of inventing one here.

Quick decision

Decide whether this is a pre-upload structure check.

This is for the finished EPUB manuscript file, not KDP account, listing, cover-upload, or approval work.

Good fit

Finished reflowable EPUB, no KDP upload yet.

The scanner can inspect package structure, metadata, navigation, links, anchors, manifest entries, cover wiring, and ZIP packaging.

Still useful

You already have a Kindle Previewer warning.

Paste the warning after selecting the EPUB so the report can compare the message with the affected path.

Not this tool

You need KDP publishing or content approval help.

Listing metadata, categories, pricing, review status, copyright, content policy, and marketing cover approval are outside this scan.

Start here

Check the exported EPUB before the KDP upload screen does.

KDP says EPUB files should meet Kindle Publishing Guidelines and recommends validating the file with Kindle Previewer before upload. If you already have the finished .epub, scan that exact file before another KDP attempt.

Matched

What it means

A KDP-ready EPUB is not just a file that opens in a reader. The package has to keep metadata, manifest, reading order, navigation, resources, anchors, and ZIP container rules coherent enough for stricter validation.

Matched

Can it be fixed automatically?

A checked repair is possible when the scan finds one clear structural correction that can be written and checked again, such as OPF wiring, manifest data, media type, navigation declaration, cover-image property, path mismatch, or ZIP wrapper order.

Matched

What to check next

Use the exported .epub file you plan to upload to KDP.

Matched

What not to assume

It does not check account or listing settings, judge content quality, redesign formatting, create missing assets, convert source files, fix paperback files, or decide KDP policy and review outcomes.

Common situations

Common KDP pre-upload check cases.

Start from the EPUB file you are about to submit.

Matched

You exported the final EPUB and want to check it before KDP.

The scan can catch package, OPF, navigation, link, anchor, manifest, cover, container, and ZIP issues before a failed upload.

Upload the final .epub and keep the report with your KDP retry notes.

Matched

Kindle Previewer already shows a warning.

Previewer may name a broad conversion or validation problem without showing the exact EPUB package path.

Paste the warning after choosing the EPUB and compare it with the affected path in the report.

Matched

The EPUB opens locally, so you want one stricter check.

Reader apps can skip broken links, stale image paths, or incomplete navigation that strict validators reject.

Use the scan to check strict structure before trusting a local reader preview.

Matched

You just exported from Word, Vellum, Atticus, Reedsy, Kindle Create, or InDesign.

Exporters can leave generated anchors, TOC wiring, image paths, or OPF fields out of sync.

Check the exported EPUB output, not the source manuscript.

Pre-upload validation phrases to check

Validate EPUB before KDP upload: check the exported .epub for EPUBCheck, Kindle Previewer, OPF, navigation, link, anchor, manifest, cover wiring, container.xml, and ZIP package blockers.

Where KDP pre-upload blockers usually appear

An author or formatter has a finished EPUB and wants to validate it before uploading to KDP, opening Kindle Previewer, or sending the file to another publishing workflow.

What it means

A finished EPUB can look ready while the package still has validation blockers.

A KDP-ready EPUB is not just a file that opens in a reader. The package has to keep metadata, manifest, reading order, navigation, resources, anchors, and ZIP container rules coherent enough for stricter validation.

Pre-upload blockers usually come from stale export paths, missing manifest entries, broken anchors, disconnected navigation, mismatched media types, wrong OPF identifiers, missing cover wiring, container.xml mistakes, or incorrect ZIP packaging.

Before you edit

Check structure before changing the manuscript or exporting again.

Do not rebuild the whole book just because you want a cleaner KDP upload. First check whether the final EPUB has a specific OPF, navigation, link, manifest, cover, container, or ZIP problem.

  1. 1Use the exported .epub file you plan to upload to KDP.
  2. 2Run the scan before editing the manuscript or re-exporting blindly.
  3. 3Check whether the report names OPF metadata, nav.xhtml, toc.ncx, XHTML links, anchors, image paths, manifest entries, cover wiring, container.xml, or ZIP packaging.
  4. 4Use checked repair only when the report shows one clear structural change and the repaired EPUB passes EPUBCheck again.
  5. 5Keep the original EPUB and source project in case the report says manual review or unsupported.
  6. 6Use KDP, Kindle Previewer, or the source workflow for approval, listing, cover upload, pricing, policy, or content decisions.

Why KDP checks it

Why KDP pre-upload checks look at EPUB structure.

KDP eBook file formats

KDP supports EPUB files that meet Kindle Publishing Guidelines and recommends checking the file with Kindle Previewer before upload.

EPUBCheck

EPUBCheck checks EPUB 2 and EPUB 3 files against the official rules and reports package, markup, link, and file-reference problems.

EPUB 3.3 package rules

The OPF file is the EPUB's map: metadata, file list, reading order, and navigation wiring. KDP and EPUBCheck use it to decide whether the book package is coherent.

Can this be fixed safely?

When a pre-upload issue can be repaired here.

When automatic repair is safe

A checked repair is possible when the scan finds one clear structural correction that can be written and checked again, such as OPF wiring, manifest data, media type, navigation declaration, cover-image property, path mismatch, or ZIP wrapper order.

When you need manual review

It does not check account or listing settings, judge content quality, redesign formatting, create missing assets, convert source files, fix paperback files, or decide KDP policy and review outcomes.

Before / after example

Before: the final EPUB has nav.xhtml but content.opf does not declare it as navigation. After: the OPF wiring can be aligned when nav.xhtml is clearly the intended file and EPUBCheck passes again. Before: no real TOC exists; rebuild it in the source tool.

Ready to retry?

Upload the EPUB for a KDP pre-upload scan.

Upload the exact .epub you plan to send to KDP. The report will show whether no supported structure blocker was found, a checked structural repair is possible, manual EPUB review is needed, or the file is outside this scanner.

Upload EPUB to scan

FAQ

Questions authors ask before uploading EPUB to KDP.

How do I validate an EPUB before uploading to KDP?

Use the finished reflowable .epub, check it with Kindle Previewer or EPUBCheck, and inspect any package errors before upload. EPUB Fixer adds affected paths and a repair/manual/unsupported decision for common structure blockers.

Does this mean KDP will accept my book?

No. It checks EPUB structure blockers and can re-run EPUBCheck after a checked repair. KDP account, content, listing, cover approval, and platform review decisions are separate.

Should I upload the DOCX or the EPUB?

Upload only the exported .epub here. DOCX, PDF, KPF, KCB, and source projects need a conversion or formatting workflow before this scan is useful.

What if Kindle Previewer already passes?

That is useful evidence. You can still use this scan when you want a path-level report, but KDP still runs its own upload and review checks.

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