EPUB error guides
KDP and EPUBCheck errors explained.
Use these guides to understand what an EPUB validation message usually means before editing the package by hand. Each guide explains the user-visible symptom, the likely EPUB structure problem, when a repaired EPUB beta download may be available, and where EPUB Fixer stops if the fix is not deterministic.
Find the right guide
Start with the message you see.
If your KDP, Kindle Previewer, or EPUBCheck report includes one of these phrases, open the matching guide first. The scanner can also identify the affected path after upload.
- Referenced resource could not be found in the EPUB
RSC_007 missing resource
- Fragment identifier is not defined
RSC_012 broken anchor
- OPF file not found in the EPUB
OPF_002 package path
- unique-identifier was not found
OPF_030 metadata
- Mimetype file entry missing or not the first file
PKG_006 ZIP packaging
- Kindle Previewer reports EPUB validation errors
Kindle Previewer report
Guide group
Broken references and anchors
Use this group when EPUBCheck or KDP points to a missing image, stylesheet, chapter file, link target, or duplicate XHTML id.
- Referenced resource could not be found in the EPUB
Plain-English guide to the RSC_007 missing resource error in EPUBCheck and KDP uploads.
- RSC-007 EPUB error
How to understand and scan RSC_007 EPUB errors caused by broken internal references.
- RSC-012 EPUB fragment error
What RSC_012 fragment identifier errors mean and when broken EPUB anchors can be repaired safely.
- EPUBCheck RSC-005 duplicate ID
What duplicate ID and RSC_005 EPUB parsing errors mean, and why many require careful review.
Guide group
Package and metadata errors
Use this group when the EPUB package cannot be opened cleanly, container.xml points to the wrong OPF file, metadata identifiers do not line up, or the mimetype entry is packaged incorrectly.
- OPF-030 unique identifier not found
How OPF_030 unique-identifier errors happen and how EPUB Fixer checks OPF metadata safely.
- OPF file not found in the EPUB
Why OPF_002 happens when container.xml points to a missing package file, and how to scan for a safe fix.
- container.xml missing in EPUB
Why META-INF/container.xml matters and when a missing EPUB container file can be rebuilt.
- Mimetype file entry missing or not first
How PKG_006 EPUB mimetype errors affect KDP uploads and when rebuilding the ZIP container can fix them.
Guide group
KDP and Kindle navigation symptoms
Use this group when the file opens but KDP or Kindle Previewer reports navigation, TOC, or preview validation problems before upload approval.
- KDP EPUB missing table of contents
Why the Kindle Go To menu may not show your EPUB table of contents, and what EPUB Fixer checks before calling it repairable.
- Kindle Previewer EPUB errors
How to turn Kindle Previewer EPUB errors into a structured repairability report before another KDP upload.
Not covered
What this page does not cover
- DOCX, PDF, KPF, KCB, or ZIP conversion into EPUB
- fixed-layout, comic, picture book, manga, or image-first EPUB repair
- DRM removal, cover design, typography, book formatting, or KDP account issues