Upload scan
Use this when Previewer gives a vague validation message.
The report can map the wording to missing resources, broken anchors, OPF metadata, navigation wiring, duplicate ids, or ZIP packaging.
EPUB error guide
Kindle Previewer EPUB validation errors
How to read Kindle Previewer EPUB validation errors, map vague messages to EPUB structure problems, and decide whether to scan, repair, or review by hand.
1. Example report output
What the Previewer scan report should show.
Kindle Previewer wording is often broad. A useful report should translate it into the affected EPUB structure area and a safe next step.
EPUBCheck message
May map to RSC_007, RSC_012, OPF_030, OPF_002, RSC_005, or PKG_006 after a scan.
KDP / Previewer wording
The book contains validation errors, a broken navigation target, or an invalid package file.
EPUB Fixer report
Maps the wording to OPF, nav, NCX, XHTML, resource, anchor, duplicate id, or ZIP packaging checks.
Do this next
Repair only when the message maps to a clear EPUB structure issue; otherwise hand it to formatting or KDP workflow review.
Do not do this
Do not keep exporting new EPUBs without saving the exact Previewer message and affected area.
If the message is about cover quality, categories, pricing, account setup, or editorial formatting, it is not an automatic EPUB repair.
2. Next step
Sort the Previewer message before another export.
Do not keep exporting blindly. First decide whether the message is structural EPUB validation, Kindle workflow setup, or a manual formatting issue.
Manual check
Use this for nav, TOC, and metadata warnings.
Confirm the intended reading order, TOC target, or publication identifier before editing package files.
Formatter handoff
Use this for layout, cover, or KDP workflow issues.
Send the Previewer message and screenshots to the person who controls the source layout or publishing setup.
3. Concrete path example
A Previewer message should be mapped to an EPUB path.
The report is useful when it turns vague wording into a file and target you can inspect.
Previewer message: navigation item points to a missing location Report shows: OEBPS/nav.xhtml -> Text/chapter3.xhtml#toc-3 Check next: does Text/chapter3.xhtml contain id="toc-3"? Decision: scan/manual review, not another blind export
If there is no EPUB path or package area behind the message, treat it as a manual publishing or formatting issue.
Quick decision
Sort the Previewer message before re-exporting.
Previewer can report EPUB structure problems and KDP workflow issues in the same session. Only the EPUB structure problems belong in this repair path.
Scan first
Previewer says the EPUB is invalid but gives vague wording.
Scan the file to map the message to OPF, nav, NCX, XHTML, resource, anchor, duplicate id, or ZIP packaging checks.
Safe fix
The message maps to a clear EPUBCheck-style issue.
Missing resources, broken anchors, OPF identifier mismatches, container paths, and mimetype packaging can often be triaged safely.
Outside scope
The message is about KDP setup or book presentation.
Account settings, pricing, categories, cover quality, editorial formatting, and fixed-layout design are not automatic EPUB structure repairs.
Start here
Save the Previewer message before trying another export.
Kindle Previewer may not show the same code as EPUBCheck. The useful clues are the wording, the package area it names, and any file path or line number in the issue panel.
What it means
Previewer errors usually mean the EPUB package is not structured the way Kindle expects, even if the book appears readable in another app. The message may not use the same code as EPUBCheck, so the useful work is to map the wording back to an affected file, package area, or validation category.
Can it be fixed automatically?
EPUB Fixer sorts these errors into automatic fixes, manual checks, and problems it should not touch. Automatic fixes usually have a clear packaged file, OPF entry, nav target, anchor, or ZIP wrapper issue that can be corrected and then pass EPUBCheck again.
What to check next
Copy the exact Kindle Previewer message before closing the report window.
What not to assume
It does not solve KDP account, tax, pricing, category, review, cover design, content quality, marketplace eligibility, or book formatting issues. It should also stop when a Previewer message depends on editorial choices such as intended reading order, footnote targets, fixed-layout design, or image-only page composition.
Common situations
Map Kindle Previewer wording to the right bucket.
Previewer often describes the symptom instead of giving a neat EPUBCheck code. Use the area it mentions.
Previewer reports missing or broken content.
This often maps to missing images, CSS, chapters, nav targets, or packaged resources.
Scan for RSC_007-style missing resources and repair only when the target is clear.
Previewer navigation or Go To looks wrong.
The issue may be nav.xhtml, toc.ncx, OPF spine wiring, or broken anchors inside TOC links.
Check navigation files and anchors before rebuilding the table of contents.
Previewer reports metadata or package errors.
These usually live in content.opf: identifiers, manifest, spine, media types, or package references.
Inspect the OPF fields named by the message and avoid changing publishing identifiers by guess.
Previewer opens the book but KDP upload still fails.
The file may have a structural warning Previewer tolerated or a KDP workflow issue unrelated to the EPUB package.
Run EPUBCheck-style scan first; if structure is clean, move to KDP account, listing, cover, or formatting review.
Previewer says conversion failed without a clear code.
A generic conversion failure can still come from a missing resource, broken nav target, OPF metadata problem, or invalid ZIP wrapper.
Save the message, scan the EPUB, and look for the first concrete file path before re-exporting.
The Kindle Previewer error wording to save
Kindle Previewer reports structural EPUB validation errors.
Where Kindle Previewer reports these EPUB problems
The EPUB may open far enough to preview, but Previewer reports package, metadata, table of contents, link, resource, anchor, duplicate id, or ZIP packaging errors before the file feels safe to upload again to KDP.
What it means
Previewer errors often map back to package, navigation, or link wiring.
Previewer errors usually mean the EPUB package is not structured the way Kindle expects, even if the book appears readable in another app. The message may not use the same code as EPUBCheck, so the useful work is to map the wording back to an affected file, package area, or validation category.
Typical causes include missing nav or NCX wiring, OPF metadata conflicts, broken resources, invalid anchors, duplicate ids, missing package files, incorrect ZIP packaging, or files renamed after export. Some Previewer warnings are Kindle-specific, but structural errors often overlap with EPUBCheck findings.
Before you edit
Turn the Previewer wording into an affected EPUB area.
Separate structural EPUB problems from publishing workflow issues. A broken nav file and a KDP category warning are not fixed in the same place.
- 1Copy the exact Kindle Previewer message before closing the report window.
- 2Check whether the issue panel names a file path, line number, package area, table of contents, missing resource, anchor, duplicate id, or ZIP packaging problem.
- 3Run EPUBCheck when possible and compare whether the same issue appears with a standard code such as RSC_007, RSC_012, OPF_002, OPF_030, or RSC_005.
- 4Find the affected OPF, XHTML, nav, NCX, CSS, image, font, or container file before editing the EPUB.
- 5Separate EPUB structure errors from KDP account, category, pricing, cover design, review, or formatting workflow issues.
- 6Reopen the repaired file in Kindle Previewer after it passes EPUBCheck because fixing the first structural error can reveal the next one.
Why KDP checks it
Why Kindle Previewer is stricter than a local reader.
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.
Can this be fixed safely?
When EPUB Fixer can help with Previewer errors.
When automatic repair is safe
EPUB Fixer sorts these errors into automatic fixes, manual checks, and problems it should not touch. Automatic fixes usually have a clear packaged file, OPF entry, nav target, anchor, or ZIP wrapper issue that can be corrected and then pass EPUBCheck again.
When you need manual review
It does not solve KDP account, tax, pricing, category, review, cover design, content quality, marketplace eligibility, or book formatting issues. It should also stop when a Previewer message depends on editorial choices such as intended reading order, footnote targets, fixed-layout design, or image-only page composition.
Before / after example
Before: Previewer shows raw messages such as a missing resource, broken TOC entry, metadata identifier problem, or invalid package file. After: the report lists affected files, groups related messages, and separates safe automatic fixes from manual work so the next KDP upload is based on a specific repair path.
Ready to retry?
Scan the EPUB when Previewer gives a vague message.
A scan is most useful when Previewer says the file is invalid but does not make the affected path obvious. The report can map the problem to OPF, nav, NCX, XHTML, resources, anchors, or ZIP packaging.
Upload EPUB to scanFAQ
Questions authors ask about Kindle Previewer errors.
What should I do when Kindle Previewer reports EPUB validation errors?
Save the exact message, check whether it mentions package, metadata, navigation, links, resources, or ZIP packaging, then scan the EPUB to see the affected path and whether the fix is safe.
Are Kindle Previewer errors the same as EPUBCheck errors?
Sometimes they point to the same structural problem with different wording. EPUBCheck codes are easier to match, but Kindle Previewer messages are still useful when they name the package area or affected file.
Should I fix Kindle Previewer errors before uploading to KDP?
Yes, when the message is about EPUB structure, package metadata, navigation, links, anchors, missing resources, or ZIP packaging. Those errors can block upload or create a Kindle file with broken navigation or missing content.
Why does my EPUB work in another reader but fail Kindle Previewer?
Many local readers tolerate invalid package wiring, missing resources, or broken anchors. Kindle Previewer validates the EPUB for the Kindle conversion path, so it can reject a file that still appears readable elsewhere.
Can EPUB Fixer handle all Kindle Previewer messages?
No. It focuses on EPUB structure problems that can be checked safely. Messages about KDP account setup, publishing metadata, pricing, categories, cover design, manuscript quality, or editorial formatting are outside the repair scope.
What if Kindle Previewer does not show an EPUBCheck code?
Use the wording and any path or package area Previewer gives you. A scan can often map the message to a standard EPUBCheck-style issue such as a missing resource, missing anchor, OPF metadata problem, or ZIP packaging problem.
Should I keep exporting until Previewer accepts the file?
Not blindly. Re-exporting can hide the first problem while creating new path, metadata, or navigation changes. Save the Previewer message, identify the affected EPUB area, and then retry with a targeted fix.