[GUI Plugin] EpubMerge - Page 39

Mandabar · 10-29-2025, 02:38 AM

Quote:

Originally Posted by JimmXinu

Calibre's epub->epub conversion, in the 'EPUB output' section, has an option for 'Flatten EPUB file structure'.

Ah. Thanks I'll give that a try!

Edit: Nope, didn't seem to work. I'll have to check to compare to be sure, and see if it made other changes to make it still work, but I went from 5 stylesheets to one. And the named styles don't match any of the original style of the sheets that were removed. Different settings for the same name I mean.
Hmm.

Edit2:Maybe it worked, and it combined the stylesheets? It's hard to tell but I can't see anything obviously wrong popping out at me... Close enough probably...

JimmXinu · 10-29-2025, 11:19 AM

Yeah, Calibre's convert is very aggressive about rewriting everything. I assume it has to use a very generic intermediate form internally because it supports so many formats.

Jennifer Stevens · 01-22-2026, 07:51 PM

Hi, JimmXinu, I've been using Epubmerge for a while. Lately my omnibus editions (a whole series merged via your plugin) have been getting rejected for upload at Draft2Digital with an error code like this:

ERROR(NCX-001): /1/toc.ncx(-1,-1): NCX identifier ("13915734-ff33-4049-849a-4f06657573ae") does not match OPF identifier ("epubmerge-uid-1747862829").

I get one line of that for every epub merged into the final file. No clue what I'm doing wrong! Maybe it's because I am using an older version of Calibre, because the newer versions blow away all my stylenames. That was unacceptable because I use those names for a reason, thanks, and want them available for final HTML massage before publication.

I prepare all my omnibus editions by adding the title page and cover and other frontmatter to the first epub in the merge, then adding the backmatter to the last epub in the merge. I've learned to give up on TOCs in omnibus merges; they seem to trigger lots of validation hate.

Most important is fixing this NCX identifier:OPF identifier match. Help?

JimmXinu · 01-23-2026, 11:39 AM

Not having seen the epubs in question, I am speculating.

But what I would guess, is that Draft2Digital is looking at the extra toc.ncx files retained by EpubMerge for UnMerging. Evidence: "/1/toc.ncx"

IMO, this is a mistake in Draft2Digital's processing. Those files should be ignored. OTOH, they are unnecessary and in a clean published book should technically be removed.

It isn't practical for EpubMerge to change the identifier in those files--they need to match the merged sub-book for UnMerge to work.

I suggest that, before doing your final merge, you go into EpubMerge's config and uncheck 'Keep UnMerge Metadata?'. Then EpubMerge won't include those extra toc.ncx (and content.opf files).

Or, if retaining UnMerge is important to you, use Edit book just before uploading to manually remove the extra toc.ncx and content.opf files--ONLY the ones with a number in front: 1/toc.ncx, 1/content.opf, 2/toc.ncx, 2/content.opf, etc.

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10-29-2025, 11:19 AM	#572
JimmXinu Plugin Developer Posts: 7,254 Karma: 5007213 Join Date: Dec 2011 Location: Midwest USA Device: Kobo Clara Colour running KOReader	Yeah, Calibre's convert is very aggressive about rewriting everything. I assume it has to use a very generic intermediate form internally because it supports so many formats.

01-22-2026, 07:51 PM	#573
Jennifer Stevens Junior Member Posts: 9 Karma: 10 Join Date: Mar 2010 Device: none	Hi, JimmXinu, I've been using Epubmerge for a while. Lately my omnibus editions (a whole series merged via your plugin) have been getting rejected for upload at Draft2Digital with an error code like this: ERROR(NCX-001): /1/toc.ncx(-1,-1): NCX identifier ("13915734-ff33-4049-849a-4f06657573ae") does not match OPF identifier ("epubmerge-uid-1747862829"). I get one line of that for every epub merged into the final file. No clue what I'm doing wrong! Maybe it's because I am using an older version of Calibre, because the newer versions blow away all my stylenames. That was unacceptable because I use those names for a reason, thanks, and want them available for final HTML massage before publication. I prepare all my omnibus editions by adding the title page and cover and other frontmatter to the first epub in the merge, then adding the backmatter to the last epub in the merge. I've learned to give up on TOCs in omnibus merges; they seem to trigger lots of validation hate. Most important is fixing this NCX identifier:OPF identifier match. Help?

01-23-2026, 11:39 AM	#574
JimmXinu Plugin Developer Posts: 7,254 Karma: 5007213 Join Date: Dec 2011 Location: Midwest USA Device: Kobo Clara Colour running KOReader	Not having seen the epubs in question, I am speculating. But what I would guess, is that Draft2Digital is looking at the extra toc.ncx files retained by EpubMerge for UnMerging. Evidence: "/1/toc.ncx" IMO, this is a mistake in Draft2Digital's processing. Those files should be ignored. OTOH, they are unnecessary and in a clean published book should technically be removed. It isn't practical for EpubMerge to change the identifier in those files--they need to match the merged sub-book for UnMerge to work. I suggest that, before doing your final merge, you go into EpubMerge's config and uncheck 'Keep UnMerge Metadata?'. Then EpubMerge won't include those extra toc.ncx (and content.opf files). Or, if retaining UnMerge is important to you, use Edit book just before uploading to manually remove the extra toc.ncx and content.opf files--ONLY the ones with a number in front: 1/toc.ncx, 1/content.opf, 2/toc.ncx, 2/content.opf, etc.

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