EPUB Error: Broken Spine Order (Duplicate or Missing idref)

OPF-054: Spine item references a manifest item that is not declared: "chapter04"

What causes this error?

The OPF spine defines the reading order of your EPUB by listing manifest item IDs in sequence. A broken spine happens when a spine itemref points to a manifest ID that doesn't exist (usually because a chapter was deleted from the manifest without removing its spine entry), or when the same ID appears in the spine twice. Both conditions fail EPUBCheck because a broken spine means the reader can't determine the correct chapter sequence.

How to fix it

  1. Open content.opf and find the <spine> section — it lists <itemref idref="..."> entries.
  2. Compare each idref value against the id attributes in the manifest section. Every idref must match exactly one manifest item id.
  3. Remove any itemref entries pointing to manifest IDs that no longer exist.
  4. If any idref appears twice in the spine, remove the duplicate.
  5. Re-validate and open the EPUB in a reader to confirm chapters appear in the correct order.

Common questions

What happens to readers if the spine is broken?

Reading apps handle it inconsistently — some skip missing chapters silently, some show a blank page, some refuse to open the file. Distribution platforms (KDP, Apple Books) typically reject the upload outright when EPUBCheck detects spine errors.

How does the spine differ from the table of contents?

The spine defines the sequential reading order used when a reader pages through the book continuously. The TOC (NCX or nav.xhtml) defines the navigational structure users see when jumping between chapters. Both can be out of sync.

Check your EPUB before uploading

The free EPUB Validator catches structure, metadata, and navigation errors — no signup, no Java, runs in the browser.

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Building your EPUB correctly from the start prevents most of these errors before they happen. See the EPUB formatting guide for the full workflow: manuscript cleanup, TOC, front matter, EPUB 3.0 generation, and validation.

Platform rejection guides: Why Draft2Digital rejects ebooks, Why Amazon KDP rejects ebooks