Some EPUB problems need a source fix, not a scanner guess.
Use EPUB Fixer when the EPUB package itself failed validation. Go back to the source tool, KDP settings, or another workflow when the fix depends on layout, account settings, or book meaning.
Upload an existing .epub file
Use your source tool or EPUB editor for layout work
Handle KDP account settings in KDP
Decision boundary
Check which kind of “unsupported” problem you have.
One group means the file is not right for this scanner. The other means the file may open, but the fix depends on your book decisions.
Before scanning
Start with the right file.
If the input is not a normal EPUB package, the scanner cannot inspect the paths, metadata, or EPUBCheck output it needs.
Have a DOCX, PDF, KPF, KCB, or ZIP archive?Matched
Export a real .epub first. This scanner needs container.xml, content.opf, packaged links, images, and EPUBCheck output; source files and generic ZIP archives do not provide the same scan path.
Have a fixed-layout, comic, manga, or picture book?Matched
Use the original design or export tool instead. Automatic structural edits can damage page-by-page layout, image placement, or reading order.
Image-first EPUB structure detected?Matched
This usually means the book is mostly page images with little XHTML text for the scanner to repair. Use the original source/export workflow or another EPUB editor instead.
Have a DRM-protected or encrypted EPUB?Matched
Use the authorized source file or publisher workflow. EPUB Fixer cannot inspect protected package files or remove access controls.
Need OCR cleanup, source image replacement, or a full re-export?Matched
Fix the source project first, then export a new EPUB. The scanner should not invent missing book content, recreate OCR text, or replace images by guesswork.
When to stop
Stop when the fix changes meaning.
Go back to your source project, EPUB editor, or KDP workflow when the next step requires design judgment, manuscript choices, or account changes.
Need cover, typography, layout, or formatting quality changes?Matched
Fix that in your source tool, design tool, or EPUB editor. EPUB Fixer checks upload-blocking structure errors, not cover design, typography, spacing, or visual quality.
Need to choose chapter meaning, section names, or reading order?Matched
Review the manuscript or source project manually. A scanner should not decide where readers should land or what a chapter should be called.
Need KDP account, pricing, category, tax, or review help?Matched
Handle that inside KDP. Those settings are outside the EPUB file, so the scanner cannot see or repair them.
Missing source files with no safe replacement inside the EPUB?Matched
Restore the original image, stylesheet, chapter, or nav file before scanning again. If there is no clear target, the report should stop at diagnosis.