MobileRead Forums - View Single Post - KFX to EPUB conversion can break page-list, while KFX Input plugin works consistently

mallomar · 07-14-2025, 05:22 PM

When converting KFX files containing page number information to EPUB using Calibre's standard conversion engine (the "Convert books" button), the resulting page-list in the nav.xhtml can sometimes be broken or have its href attributes stripped. While this doesn't seem to happen with every single KFX file, I have found it to be a frequent issue. When it occurs, it makes the reference page numbers unusable in compliant e-reader software like KOReader and causes the EPUB to fail epubcheck with pathing errors (RSC-007).

This issue does not appear to happen when converting the same KFX files using the KFX Input plugin's dedicated conversion feature, which has been consistently successful.

Steps to Reproduce:

Start with a KFX-format book that is known to contain a page map where this issue can be reproduced.
Convert the book to EPUB using Calibre's standard "Convert books" feature.
Inspect the output EPUB. The <nav epub:type="page-list"> section within nav.xhtml may have incorrect or missing href attributes for its list items. For example, <a>1</a> instead of <a href="OEBPS/file.xhtml#page_1">1</a>.
Now, take the same original KFX file and convert it again, but this time use the KFX Input plugin's conversion method (e.g., right-click the book -> KFX Input -> Convert to EPUB).
Inspect this second EPUB. Its page-list is generated correctly with complete and valid href attributes.

There appears to be a discrepancy in how Calibre's main conversion engine and the KFX Input plugin handle the page map data from some KFX source files. The standard engine can fail to correctly reconstruct the page-list navigation, leading to a broken EPUB. The plugin's method, however, seems to produce a correctly structured and functional EPUB more reliably.

I can provide scrambled versions of the EPUBs generated by both Calibre's standard converter and the KFX Input plugin for a direct comparison if that would be helpful for debugging.

My System Details:

Calibre Version: [8.16]
Operating System: [macOS Sequoia 15.6]

(I am posting this here because I was unable to use the official bug tracker. This is the second time I've tried to report this bug on Launchpad over the last few weeks, and I receive an "Oops!" error page each time I try to log in.)

07-14-2025, 05:22 PM	#1
mallomar Connoisseur Posts: 70 Karma: 8682 Join Date: May 2018 Device: Onyx Boox Note Air 2, Kindle Oasis 2	KFX to EPUB conversion can break page-list, while KFX Input plugin works consistently When converting KFX files containing page number information to EPUB using Calibre's standard conversion engine (the "Convert books" button), the resulting page-list in the nav.xhtml can sometimes be broken or have its href attributes stripped. While this doesn't seem to happen with every single KFX file, I have found it to be a frequent issue. When it occurs, it makes the reference page numbers unusable in compliant e-reader software like KOReader and causes the EPUB to fail epubcheck with pathing errors (RSC-007). This issue does not appear to happen when converting the same KFX files using the KFX Input plugin's dedicated conversion feature, which has been consistently successful. Steps to Reproduce: Start with a KFX-format book that is known to contain a page map where this issue can be reproduced. Convert the book to EPUB using Calibre's standard "Convert books" feature. Inspect the output EPUB. The <nav epub:type="page-list"> section within nav.xhtml may have incorrect or missing href attributes for its list items. For example, <a>1</a> instead of <a href="OEBPS/file.xhtml#page_1">1</a>. Now, take the same original KFX file and convert it again, but this time use the KFX Input plugin's conversion method (e.g., right-click the book -> KFX Input -> Convert to EPUB). Inspect this second EPUB. Its page-list is generated correctly with complete and valid href attributes. There appears to be a discrepancy in how Calibre's main conversion engine and the KFX Input plugin handle the page map data from some KFX source files. The standard engine can fail to correctly reconstruct the page-list navigation, leading to a broken EPUB. The plugin's method, however, seems to produce a correctly structured and functional EPUB more reliably. I can provide scrambled versions of the EPUBs generated by both Calibre's standard converter and the KFX Input plugin for a direct comparison if that would be helpful for debugging. My System Details: Calibre Version: [8.16] Operating System: [macOS Sequoia 15.6] (I am posting this here because I was unable to use the official bug tracker. This is the second time I've tried to report this bug on Launchpad over the last few weeks, and I receive an "Oops!" error page each time I try to log in.)