EPUB FixerKDP upload error scanner

EPUB error guide

OPF_029: EPUB media type does not match the file

Use this when EPUBCheck says a file does not match its declared media type. The scan compares content.opf with the file path and extension, then shows whether only the manifest needs to change.

Scan EPUB structureSee an example report

Your error

EPUBCheck reports OPF_029.

The file exists, but content.opf describes it as a different type, such as a PNG image declared as image/jpeg.

What the scan checks

The file path and its manifest entry.

The report compares the packaged path, file extension, declared media-type, and EPUBCheck message before suggesting a change.

Stop if

The file is missing, damaged, or unclear.

Do not change the manifest when the asset itself needs to be restored, replaced, or exported again.

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

  • Manifest media-type does not match the file extension
  • OPF-029 media-type does not match the file
  • Image extension does not match file type
  • The file does not appear to match the media type

Use this guide when

Your message matches "Manifest media-type does not match the file extension" 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 "Manifest media-type does not match the file extension" 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 the OPF_029 report should show.

A useful report should connect the manifest item to the referenced file instead of only saying the media type is wrong.

EPUBCheck message

ERROR(OPF-029): OEBPS/content.opf: Item "images/cover.png" does not appear to match the media type image/jpeg.

Plain explanation

The media type in content.opf does not match the file EPUBCheck inspected.

EPUB Fixer report

Manifest href images/cover.png is declared as image/jpeg, but the packaged file extension is .png.

Do this next

Verify the file first. Change the media-type only when the file is correct and the manifest entry is the only mismatch.

Do not do this

Do not rename the file, swap in a new asset, or guess a different format just to clear OPF_029.

A safe fix keeps the same file and updates only the manifest media-type after the file has been verified.

2. Next step

Choose scan, safe manifest repair, or source export review.

The next step depends on whether the EPUB already contains the right file and only the OPF manifest entry is wrong.

Scan first

You only have the validator message.

Upload the EPUB so the report can show the manifest href, the packaged file path, and the exact media-type mismatch before you edit content.opf.

Matched

Safe repair

The file is verified and only the media type is wrong.

Update the manifest media-type when the file format is known and the manifest is the only mismatch, then validate again.

Manual review

The file itself is unclear or exported incorrectly.

Stop when the asset may need re-export, replacement, or author or EPUB editor judgment instead of a manifest-only correction.

3. Concrete path example

A typical OPF_029 manifest mismatch.

The report should show the same href in content.opf and the real file it points to inside the EPUB.

EPUBCheck:
ERROR(OPF-029): OEBPS/content.opf: Item "images/cover.png" does not appear to match the media type image/jpeg.

Report:
Manifest href: images/cover.png
Declared media-type: image/jpeg
Packaged file: OEBPS/images/cover.png
File extension: .png
Fix decision: verify that the file is a PNG, then update the manifest

If the file itself is wrong or missing, the next step is source repair, not a manifest-only change.

Quick decision

Decide whether this is only a manifest mismatch.

A wrong media-type can be a small package-only fix. It should not turn into renaming files, swapping assets, or guessing the book's intended resource format.

Scan first

You do not know whether the packaged file is correct.

Use the scan to connect the manifest href to the real packaged file before changing content.opf.

Matched

Safe fix

The file format is verified and the manifest is wrong.

Update only the manifest media-type, keep the same file path, and validate the EPUB again.

Stop

The file itself needs replacement or export changes.

Do not guess when the asset may be the wrong file, the wrong conversion output, or part of a larger packaging problem.

Start here

Check the packaged file before changing content.opf.

OPF_029 means EPUBCheck found that the file and its content.opf media type do not agree. Verify the file before editing the manifest.

Matched

What it means

The EPUB package points to a real file, but content.opf describes that file as the wrong resource type. Kindle and EPUBCheck use the OPF manifest to understand whether a file is an image, stylesheet, XHTML document, SVG, font, or another packaged asset.

Matched

Can it be fixed automatically?

A repair is possible when the file exists, the href is correct, and the file format has been verified. The change updates only the manifest media-type and keeps the same file path.

Matched

What to check next

Copy the exact manifest href and declared media-type from content.opf before making any change.

Matched

What not to assume

It should stop for manual review when the asset itself may be wrong, missing, duplicated, or part of a broader export problem. The tool should not swap files, rename assets, or guess a replacement format.

Common situations

Common OPF_029 cases.

Start with the file path named by the manifest and verify that file before changing anything.

Matched

A PNG image is declared as JPEG.

The file exists and the href already points to cover.png, but content.opf still says image/jpeg.

Set media-type to image/png, then validate again.

Matched

An image file has the wrong manifest media type.

The asset exists, but the manifest entry does not match the actual image format or file extension.

Update the manifest entry only if the packaged file is the intended asset.

A stylesheet, XHTML, or SVG file is declared with the wrong type.

The manifest href points to a real packaged file, but the media-type belongs to another resource category.

Correct the OPF media-type only when the file path and resource type are unambiguous.

The file was converted or renamed incorrectly during export.

The extension, packaged file, and actual resource may no longer agree after a source-tool export or manual ZIP edit.

Re-export or replace the source asset when the file itself is wrong, instead of patching content.opf blindly.

The OPF_029 media-type mismatch text

OPF_029: The manifest media type does not match the referenced file.

Where OPF_029 usually appears

EPUBCheck, Kindle Previewer, or KDP finds a manifest item in content.opf whose media-type does not match the actual packaged file or file extension.

What it means

OPF_029 usually means the manifest entry and the packaged file disagree.

The EPUB package points to a real file, but content.opf describes that file as the wrong resource type. Kindle and EPUBCheck use the OPF manifest to understand whether a file is an image, stylesheet, XHTML document, SVG, font, or another packaged asset.

Common causes include an image converted from JPG to PNG without updating content.opf, files renamed after export, manual ZIP edits, assets copied between EPUBs, and source tools that leave an old media-type value in the manifest.

Before you edit

Compare content.opf with the referenced file.

Do not change media-type just because the extension looks familiar. First confirm the manifest href, the real file extension, and whether the file was renamed, converted, or exported incorrectly.

  1. 1Copy the exact manifest href and declared media-type from content.opf before making any change.
  2. 2Open the packaged file at that href and confirm whether the extension and real file type match the declared media-type.
  3. 3Check whether the mismatch is limited to content.opf or whether the asset itself was exported, renamed, or converted incorrectly.
  4. 4Keep the same href when the packaged file is already correct and only the media-type is wrong.
  5. 5Stop and review the source export when fixing OPF_029 would require replacing the asset, renaming files, or guessing which format the book intended to use.

Why KDP checks it

Why EPUBCheck and Kindle care about the manifest media type.

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.

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 a media-type mismatch is safe to repair.

When automatic repair is safe

A repair is possible when the file exists, the href is correct, and the file format has been verified. The change updates only the manifest media-type and keeps the same file path.

When you need manual review

It should stop for manual review when the asset itself may be wrong, missing, duplicated, or part of a broader export problem. The tool should not swap files, rename assets, or guess a replacement format.

Before / after example

Before: content.opf declares images/cover.png as image/jpeg. After: the same manifest item is updated to image/png and the EPUB is validated again. Before: the EPUB contains the wrong exported image file entirely; that should go back to the source project instead of being guessed in place.

Ready to retry?

Scan the EPUB before editing the manifest item.

The report shows the manifest item, packaged path, file extension, declared media-type, and EPUBCheck message so you can decide whether the manifest alone is wrong.

Upload EPUB to scan

FAQ

Questions authors ask about OPF_029.

What does OPF_029 media-type mismatch mean?

It means content.opf declares a file as one resource type, such as image/jpeg, while the packaged file looks like another type, such as image/png.

Can EPUB Fixer repair a media-type mismatch automatically?

Yes, but only when the file format is verified, the path is correct, and the fix is limited to updating the OPF manifest entry. The repaired EPUB still has to pass EPUBCheck again.

Should I rename the file to match the manifest?

Not by default. If the packaged asset is already the intended file, the safer change is usually to fix content.opf. Rename or replace the file only when the source export itself is wrong.

Why can this still fail in KDP if the image opens locally?

Local readers may still show the image, but EPUBCheck and Kindle use the OPF manifest to validate whether the package inventory describes the file correctly.

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