[Conversion Plugin] KFX Input

[mikae1]

So, I'm pulling my hair because Amazon decided to automatically convert my Push to Kindle documents to KFX.

I have now disabled "Automatic Book Updates" in the kindle.amazon.com settings.

KFX Input plugin makes it possible to open my older KFX documents, but does not work with the newer ones on my device:

calibre, version 8.13.0
ERROR: Loading book failed: Failed to open the book at /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx. Click "Show details" for more info.

Failed to convert book: /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx with error:
KFX metadata reader (from KFX Input) activated for /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx
Import symbol table YJ_symbols version 10 max_id 842(+9=851) exceeds known table size 816(+9=825)
InputFormatPlugin: KFX Input running
on /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx
Software versions: KFX Input 1.51.0, calibre 8.13, Linux-6.16.7-200.fc42.x86_64-x86_64-with-glibc2.42
KFX Input plugin help is available at https://www.mobileread.com/forums/showthread.php?t=291290
Converting /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx
Processing container: /Kindle/documents/Downloads/Items02/A Small Web July_EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW.kfx
WARNING: Import symbol table YJ_symbols version 10 max_id 842(+9=851) exceeds known table size 816(+9=825)
WARNING: Unexpected nav_type: $798
WARNING: Feature/content mismatch: yj_jpegxr_sd=1 has_jpeg_xr_image=False
WARNING: Unknown symbols feature: max_id-851
Features: CanonicalFormat-2, kfxgen.positionMaps-2, kfxgen.textBlock-1, reflow-style-1, yj_jpegxr_sd-1
Metadata: ASIN=EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW, asset_id=CR!0VNYP176WN27ZEK3F4Q02XBDB47M, author=smallcypress.bearblog.dev, book_id=bFJNOy4nQOCQohBo39TiDw0, cde_content_type=PDOC, content_id=EIY2QMZRV2AUCPLU4NVRYHGWYGCTDCMW, cover_image=667x1000, creator_version=2.15.0, description=..., file_creator=YJConversionTools, is_sample=False, issue_date=2025-07-25, kfxgen=20.12.238.0, language=en, nested_span=enabled, pages=4, publisher=, reading_orders=1, selection=enabled, title="A Small Web July"
ERROR: Unexpected Ion symbols used: $798, $799, $801
Converting book to EPUB 3
ERROR: nav_container n1R has unknown type: $798
ERROR: nav_container n1R nav_unit has extra data: {$238: $799, $241: {$244: 'heading-nav-unit'}, $246: {$155: 894, $143: 0}, $247: [{$241: {$244: 'heading-nav-unit'}, $246: {$155: 894, $143: 0}}]}
ERROR: nav_container n1R nav_unit has extra data: {$238: $801, $241: {$244: 'heading-nav-unit'}, $246: {$155: 895, $143: 0}, $247: [{$241: {$244: 'heading-nav-unit'}, $246: {$155: 895, $143: 0}}, {$241: {$244: 'heading-nav-unit'}, $246: {$155: 896, $143: 0}}]}
Failed to run pipe worker with command: from calibre.srv.render_book import viewer_main; viewer_main()
Traceback (most recent call last):
  File "calibre_plugins.kfx_input.__init__", line 119, in convert
Exception: Unexpected Ion symbols used: $798, $799, $801
nav_container n1R has unknown type: $798
nav_container n1R nav_unit has extra data: {$238: $799, $241: {$244: 'heading-nav-unit'}, $246: {$155: 894, $143: 0}, $247: [{$241: {$244: 'heading-nav-unit'}, $246: {$155: 894, $143: 0}}]}
nav_container n1R nav_unit has extra data: {$238: $801, $241: {$244: 'heading-nav-unit'}, $246: {$155: 895, $143: 0}, $247: [{$241: {$244: 'heading-nav-unit'}, $246: {$155: 895, $143: 0}}, {$241: {$244: 'heading-nav-unit'}, $246: {$155: 896, $143: 0}}]}

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "runpy.py", line 198, in _run_module_as_main
  File "runpy.py", line 88, in _run_code
  File "site.py", line 47, in <module>
  File "site.py", line 43, in main
  File "calibre/utils/ipc/worker.py", line 194, in main
  File "<string>", line 1, in <module>
  File "calibre/srv/render_book.py", line 851, in viewer_main
  File "calibre/srv/render_book.py", line 842, in render_for_viewer
  File "calibre/srv/render_book.py", line 819, in render
  File "calibre/ebooks/oeb/iterator/book.py", line 64, in extract_book
  File "calibre/customize/conversion.py", line 242, in __call__
  File "calibre_plugins.kfx_input.__init__", line 130, in convert
calibre.ebooks.conversion.ConversionUserFeedBack: {"msg": "<b>Cannot convert ?</b><br><br>Exception(\"Unexpected Ion symbols used: $798, $799, $801\\nnav_container n1R has unknown type: $798\\nnav_container n1R nav_unit has extra data: ($238: $799, $241: ($244: 'heading-nav-unit'), $246: ($155: 894, $143: 0), $247: [($241: ($244: 'heading-nav-unit'), $246: ($155: 894, $143: 0))])\\nnav_container n1R nav_unit has extra data: ($238: $801, $241: ($244: 'heading-nav-unit'), $246: ($155: 895, $143: 0), $247: [($241: ($244: 'heading-nav-unit'), $246: ($155: 895, $143: 0)), ($241: ($244: 'heading-nav-unit'), $246: ($155: 896, $143: 0))])\")", "level": "error", "det_msg": "", "title": "KFX conversion failed"}

Is there any way to convert these newer documents?

I really wish there was a better device out there to buy... I need to be able to push documents from my browser and I need to be able to make highlights on the device that I can later open on my computer. I don't want a subscription service for this basic function to work. I can plug the device in with a USB cable to view the notes.

[mikae1]

All KFX documents from 2023-03-12 (ISO 8601 date) and later will not open. A KFX document from 2023-03-11 (and all documents before that) opens just fine.

[JSWolf]

If you are using a new enough Kindle with new enough firmware, then you cannot remove the DRM. If you are using K4PC, then that's your problem.

[Ma'am-I-Am]

@mikae1
You only mentioned documents, not articles, so I'm unsure if this applies.
If you're using Push to Kindle by fivefilters.org you could try downloading your articles as epub or mobi then add them to your Kindle using USB and see if you can make notes.
You could also download the articles as PDF (still using Push to Kindle), then use Send to Kindle website. According to Amazon, PDFs with adjustable layout sent via S2K to a Scribe will allow notes, highlights, etc.

[jhowell]

Originally Posted by mikae1

Software versions: KFX Input 1.51.0

You are using a very old version of this plugin. You need to update in order to convert that book.

[mikae1]

Originally Posted by jhowell

You are using a very old version of this plugin. You need to update in order to convert that book.

Oh, sorry. Downloaded it from GitHub I belive. I realize now that the correct source is this thread. Downloaded it from here and it now works!

[jhowell]

Originally Posted by mikae1

Oh, sorry. Downloaded it from GitHub I belive. I realize now that the correct source is this thread. Downloaded it from here and it now works!

Calibre is itself the best source for up to date plugins, except for those that deal with DRM.

[mickjs]

Originally Posted by Jakque

Mac OS Tahoe 26.0.1 Calibre 8.13

Calibre has slowed down immensely. When I click the mouse on a book, I get the spinning pinwheel. It lasts for about thirty seconds, with a severe response lag when loading a book's information. The entire experience takes a few minutes with intermittent pinwheel activity. Does that make sense?

I had this issue as well. Updating to the new macOS 26.1 seems to have fixed it (thus far).

[tomsem]

Originally Posted by mickjs

I had this issue as well. Updating to the new macOS 26.1 seems to have fixed it (thus far).

If library is synched to cloud (I know it's discouraged but I do it anyway) then there will be a delay if it has to be downloaded again.

[JSWolf]

Originally Posted by tomsem

If library is synched to cloud (I know it's discouraged but I do it anyway) then there will be a delay if it has to be downloaded again.

I also sync my calibre libraries to the cloud. But I only do a one-way sync so there is no way my libraries get written to from the cloud without my doing it.

[User11235]

Ok, I haven't done this in awhile, need a little help...

I'm on Windows 11, I have the latest calibre and all the plugins, and it was all working exactly the way it's currently setup the last time I tried it (I haven't uninstalled/reinstalled anything, my Kindle SN is still input, etc)

I do Kobo books all the time, with the Obok tool... It's just been awhile now that I've done a Kindle book...

Anyway, I have an older Kindle eInk device, I just bought a book that was published back in 2015, and it's on my Kindle now... I've tried connected my Kindle to calibre and adding the book to my library from the device... I've tried importing the KFX file from my library (by navigating to where it is on the Kindle, in the 'documents' folder)...

It imports to my library as an un-openable KFX file... Am I just out of luck here, or am I not doing it correctly? Like I said, it worked fine last time I tried it -- maybe a year ago now -- and nothing has changed with my calibre setup except updates (to calibre and all plugins)... I just don't remember if there were other steps to do, besides simply importing the file...

Thanks y'all.

[Martinoptic]

This might help? https://www.mobileread.com/forums/sh...d.php?t=361503

[jhowell]

Originally Posted by User11235

It imports to my library as an un-openable KFX file... Am I just out of luck here, or am I not doing it correctly?

If it fails to open due to a DRM error then ask for help in the Issues section at the GitHub site hosting the DeDRM plugin.

If it fails to open for some other reason post more details of the error you are seeing in this thread.

[User11235]

Thanks for the help, I really appreciate it... I ended-up solving it myself late last night, but my comment wasn't posted/approved yet, or I would have edited it...

Anyway, I finally stumbled upon a blog post that reminded me to do a conversion after importing... So I converted the KFX file to EPUB and that worked great, now I can open/read the EPUB version...

Thanks again, I'm so glad these tools and this forum exist!

[digitalstew]

Hey all, new to his forum (but not Calibre and the DeDRM and KFX Input plugins). It looks like something has now changed from Amazon. I normally connect my Kindle Scribe (2024) to my Mac and use Calibre to import and convert the KFX books to DRM-free ePubs. This process has worked flawlessly.

However, a handful of more recent Amazon ebooks are now showing up as KFX-ZIP files and I cannot remove the DRM from them. I have the latest versions of both DeDRM and KFX-Input.

I assume this is something Amazon has done to further lock down ebooks, and I assume there needs to be an update to KFX-Input to do these new conversions. Am I correct in that assumption or is there something I need to do on my side?