ERROR(NCX-001) - NCX identifier Not Match


How to fix the "ERROR(NCX-001) - NCX identifier ... does not match OPF identifier ..." error?



When you validate a EPUB 2.0 package with EpubCheck, you may see the following error:

C:\fyicenter> java -jar epubcheck.jar Error-NCX-ID-Not-Match-2.0.epub
Validating using EPUB version 2.0.1 rules.
ERROR(NCX-001): Error-NCX-ID-Not-Match.epub/navigation.xml(-1,-1): 
 NCX identifier ("Hello") does not match 
 OPF identifier ("").

Check finished with errors
Messages: 0 fatals / 1 error / 0 warnings / 0 infos

EPUBCheck completed

Download Error-NCX-ID-Not-Match-2.0.epub, and unzip it. You see the package file "package.opf" defines "" as the EPUB package's unique identifier:

<package xmlns="" version="2.0" 
  <metadata xmlns:dc="">
    <dc:identifier id="MyID"></dc:identifier>

But the navigation file (or NCX file) refers it as "Hello":

<?xml version="1.0" encoding="utf-8"?>
<!-- navigation.xml
  Copyright (c) 2018 
<ncx xmlns="" version="2005-1">
        <meta content="Hello" name="dtb:uid"/>
        <navPoint id="link1">
            <content src="/content.xhtml"/>

You can fix the error by changing content="Hello" to content="".


Errors in GeographyofBliss_oneChapter.epub

ERROR(OPF-030) - unique-identifier Not Found

Common Errors in Reported by EpubCheck

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2022-11-04, 908🔥, 0💬