EPUBCheck validation errors with EPUB export

Report · Jul 24, 2024

Hi All,

Thank you in advance for your assistance. Seems like validation issues with this application are common.

First, the basics:

I am using InDesign 2024 (v19.5)

I am attempting to export my book with a fixed layout.

Selected Multi Level (TOC Style) for Navigation TOC.

Book looks beautiful in Apple Books reader

This is my first attempt to upload a book to Apple Books. Like a fool, I thought it would be a little more straightforward than this...

After installing and running EPUBCheck against my epub file, I am receiving the issues below. Apologies for the long list, but thought it might be helpful to include the entire listing. I'm assuming that the only entries I need to solve are those preceeded by ERROR. Also, if one of you know of a resource I can visit to educate myself on correcting these issues, I will be happy to visit and review. Just thought a "standard" export via InDesign would product a valid file.

Please let me know if I can provide additional info to assist.

Many thanks!

----------------------------

Validating using EPUB version 3.3 rules.
WARNING(OPF-053): FundStudyEBook_07_10_24.epub/OEBPS/content.opf(11,32): Date value "08/03/2022" does not follow recommended syntax as per http://www.w3.org/TR/NOTE-datetime:[For input string: "08/03/2022"] is not an integer.
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-8.xhtml(14,89): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-8.xhtml(25,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-8.xhtml(36,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(14,89): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(25,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(36,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(47,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(58,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch1_07_29_22-9.xhtml(69,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch2_07_30_22-4.xhtml(20,89): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
ERROR(HTM_061): FundStudyEBook_07_10_24.epub/OEBPS/FundStudy_Ch2_07_30_22-4.xhtml(31,86): "data-idGenObjectState" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(18,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/AvenirNext-Medium.ttc" refers to non-standard font type "application/x-font-ttf".
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(102,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/HiraMinProN-W3.ttc" refers to non-standard font type "application/x-font-ttf".
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(108,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/HiraMinProN-W6.ttc" refers to non-standard font type "application/x-font-ttf".
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(126,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/Lato-Medium.ttf" refers to non-standard font type "application/x-font-ttf".
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(132,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/Lato-Regular.ttf" refers to non-standard font type "application/x-font-ttf".
INFO(CSS-007): FundStudyEBook_07_10_24.epub/OEBPS/css/idGeneratedStyles_0.css(138,2): Font-face reference "https://3c663a86-e5ae-4c5e-a3e3-343afa71aa7e.epubcheck.w3c.org/OEBPS/font/Lato-Semibold.ttf" refers to non-standard font type "application/x-font-ttf".
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/AcuminConcept-BoldItalic.otf(-1,-1): File "OEBPS/font/AcuminConcept-BoldItalic.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/AcuminProCond-Bold.otf(-1,-1): File "OEBPS/font/AcuminProCond-Bold.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/AvenirNext-Medium.ttc(-1,-1): File "OEBPS/font/AvenirNext-Medium.ttc" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GaramondPremrPro-BdIt.otf(-1,-1): File "OEBPS/font/GaramondPremrPro-BdIt.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GaramondPremrPro-It.otf(-1,-1): File "OEBPS/font/GaramondPremrPro-It.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GaramondPremrPro-MedIt.otf(-1,-1): File "OEBPS/font/GaramondPremrPro-MedIt.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GaramondPremrPro-SmbdIt.otf(-1,-1): File "OEBPS/font/GaramondPremrPro-SmbdIt.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GaramondPremrPro.otf(-1,-1): File "OEBPS/font/GaramondPremrPro.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GoudyOldSty-Bol.otf(-1,-1): File "OEBPS/font/GoudyOldSty-Bol.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GoudyOldSty-Reg.otf(-1,-1): File "OEBPS/font/GoudyOldSty-Reg.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/GoudyOldSty-RegIta.otf(-1,-1): File "OEBPS/font/GoudyOldSty-RegIta.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/HiraMinProN-W3.ttc(-1,-1): File "OEBPS/font/HiraMinProN-W3.ttc" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/HiraMinProN-W6.ttc(-1,-1): File "OEBPS/font/HiraMinProN-W6.ttc" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/Lato-Medium.ttf(-1,-1): File "OEBPS/font/Lato-Medium.ttf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/Lato-Regular.ttf(-1,-1): File "OEBPS/font/Lato-Regular.ttf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/Lato-Semibold.ttf(-1,-1): File "OEBPS/font/Lato-Semibold.ttf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/LTCGoudyOldstylePro-BoldItalic.otf(-1,-1): File "OEBPS/font/LTCGoudyOldstylePro-BoldItalic.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionConceptItalic_9.000opsz_1ital.otf(-1,-1): File "OEBPS/font/MinionConceptItalic_9.000opsz_1ital.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionConceptRoman_20.000opsz_0ital.otf(-1,-1): File "OEBPS/font/MinionConceptRoman_20.000opsz_0ital.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionConceptRoman-Display.otf(-1,-1): File "OEBPS/font/MinionConceptRoman-Display.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionConceptRoman-Regular.otf(-1,-1): File "OEBPS/font/MinionConceptRoman-Regular.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionPro-Bold.otf(-1,-1): File "OEBPS/font/MinionPro-Bold.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionPro-It.otf(-1,-1): File "OEBPS/font/MinionPro-It.otf" is encrypted, its content will not be checked.
INFO(RSC-004): FundStudyEBook_07_10_24.epub/OEBPS/font/MinionPro-Regular.otf(-1,-1): File "OEBPS/font/MinionPro-Regular.otf" is encrypted, its content will not be checked.
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(17,66): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(71,63): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(77,63): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(83,60): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(89,61): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
ERROR(PKG-026): FundStudyEBook_07_10_24.epub/META-INF/encryption.xml(95,62): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").

Check finished with errors
Messages: 0 fatals / 17 errors / 1 warning / 30 infos

EPUBCheck completed

Report · Jul 24, 2024

Well, that's quite the mess you have there. 🙂

I'll start with the tired old warning that fixed-page layout (FXL) is a largely obsolete and deprecated format, especially for text books — it is suitable only for a select range of "picture page" books like children's books, graphic novels and how-to books with elaborate diagram pages. If you chose it because you thought it was simpler or the "obvious" choice for an e-book... you chose poorly. Reflowable EPUB is preferred in all cases, especially for all-text or text-heavy books.

Second, FXL is nearly impossible to fix; it's very much a "you get what you get" result with very few ways to fix, adjust or tweak the result. That it "renders beautifully" in the reader but fails the often pointless nitpickiness of validation speaks volumes; validation itself is a sort of obsolete practice dating from the "build a book" era in which it was possible to make many mistakes in hand-assembling an EPUB file.

A further point is that EPUB readers vary widely, and Apple's is a ways off the standard. It's not really relevant to your case, but it's best to proof/check your book in a more standard (and standards-compliant) reader such as Calibre. If your market is Apple, you will have to tweak a version that conforms to their unique rendering choices. (Ditto for Kindle; everyone else will just have to take their chances.)

The resource errors at the end are font-related, which can come from a number of causes. EPUB font errors are solved, in the main, by not embedding the fonts — which is optional in reflowable format, required in FXL. The most common cause of font errors is using fonts not licensed or otherwise enabled for e-book export, but it can be many things.

Unfortunately, I simply don't recognize that first block of errors. They probably stem from some faulty combination of cross-references, TOC links or the like but the errors themselves tell me nothing useful.

The starting point, to me, would be to recast this as a reflowable EPUB and eliminate the font issues by not spec'ing or embedding fonts in the export. If you want facsimile print pages, the solution is PDF, not FXL EPUB — again, as "obvious" as FXL seems, it's not really a solution to anything any more.

And, not to make any sales pitch, but the only comprehensive, professional-level reference to EPUB creation using ID is the book noted below. It does not say much about FXL, though. 🙂 You can also find useful tutorial/reference essays here: Digital Publishing Basics.

Happy to help you work this through, though, given the limitations of the medium.

┋┊ InDesign to Kindle (& EPUB): A Professional Guide, v3.1 ┊ (Amazon) ┊┋

Report · Jul 24, 2024

Thank you for the response James.

Unfortunately, my book is HEAVY with graphics and photos. Believe me, if I could had opted for reflowable, I would have taken that approach. Given the association of text to photos/graphics, fixed layout is my only option.

This book was published in print format two years ago and I am only now looking to move to epub. Considering your feedback regarding the shortcomings of fixed layout, along with the notion that reflowable will not work for me, I'll look into PDF and see how that looks.

This validation process is utterly useless. Seems to be another example of process impeding progress. Sure seems like there should be a better way, but understand I am screaming into the black void. Read many frustrated comments in other ID posts and realize I am but one of many frustrated with Apple Book's submission process.

Many thanks!

Report · Jul 24, 2024

Some additional thoughts —

Yes, Apple is extremely picky, as is consistent with their nature of seeking perfection in all things. Can't really complain that they want third-party products to meet at least a high technical standard. That said, many of the complaints are justified.

And that said, I've never found Apple/iTunes a market worth all the effort. For e-books, there's Kindle, and somewhere way behind that is iTunes, and down at floor level are all the EPUB vendors like Smashwords. Maybe iTunes would be a great market, but I've sold about four copies total on the rest of the non-Amazon portals. I am of the opinion that iTunes is greater in reputation and prestige than in actual sales for non-NYTBSL authors.

It's possible to get a clean FXL out of ID, but as the projects usually start with a book built and optimized for print, it's an uphill slog. You can get away with all kinds of slop and slack and patchwork for print (via PDF), but e-books demand absolutely meticulous structure, styles, organization etc., and FXL goes a level above that because you can't do much except hit export and hope. So your path to FXL is going to involve a lot of cleanup, organization, patching little faults, etc. (It is easier if you build for e-book from scratch and know what's needed, but converting a print book is tough.)

I'd reduce the number of faces and fonts as much as you can, as well — two families, four faces each is optimal. And then use genuine Adobe fonts for absolutely everything, to help avoid the licensing, encryption and other validation errors.

PDF — is a great document format. It's a lousy publication format because it's almost impossible to protect with DRM. I don't know of any commercial portals that sell protected PDFs except at a fairly high and expensive level. (I have one client whose textbook is PDF and requires a central, server-managed rental/access scheme that's quite expensive.)

And as for "too complex for reflowable" — I hear that a lot. Sometimes it's even true, but you can get astonishing complexity into a reflowable EPUB (including images, charts, tables, text pulls, lists and more) if you know what you're doing AND — most importantly — let go of the idea that only a structured page can present your content.

Yeah, it should all be easier. But we're stuck with the lumpy, poorly supported, standards-avoiding mess that is EPUB for either the end or interim format, and it is tough to beat that mess into a good result.

┋┊ InDesign to Kindle (& EPUB): A Professional Guide, v3.1 ┊ (Amazon) ┊┋

Report · Aug 05, 2024

- UPDATE -

I have identified and resolved the issues I was experiencing.

The object errors related to three clickable slideshows I embedded within the text. Guess I was wrong to think that interactive functionality within an ebook would allow interactivity. After removing the slideshows the error disappeared.

For the issues related to the fonts, I replaced the offending type with those that were recognized which took care of those issues. After that, the epub validated with zero errors.

I have successfully uploaded my fixed-page layout to Apple Books and it is now available through the store. Just had to take a step back and progress through each issue methodically.

Report · Aug 05, 2024

Yay and congrats!

Not saying any of this applies to you or your project; just pontificating —

There is a sort of free-floating belief that interactive features will sort of work on anything with a screen, and (often) that they just sort of exist in a vacuum, as an independent entity. Time and time again we see newcomer queries here like "I want to build a fully interactive children's book/training module that will [do very Star-Trekky things like I saw in a museum once]." That such things exist, as fully developed apps/applets or programming on a hefty multimedia platform, is lost in the hazy vision that basic buttons, embeds and forms in layout apps are the same thing.

In theory, PDF and EPUB can support advanced multimedia and interactive features. In practice, anything that is not a fully developed app emulating a children's book or the like is going to be limited to the intersection of the format/standard itself and the capabilities of the platform/app/viewer it uses. In PDF, it's another perpetual topic that something developed on a desktop and tested in Acrobat Pro "doesn't work for all my friends and co-workers on their mobile devices and browsers." — because those PDF viewers are nonstandard, incomplete and lack most advanced feature support.

EPUB: even worse. EPUB on a proprietary platform like Apple: worser. You cam often hack it together one way or the other, but the real world bites back.

But fonts, yeah, you have to use industry-standard, licensable fonts if you insist on embedding them. Non-licensable OS or foundry fonts, or junk fonts downloaded from somewhere, will generate errors everywhere they go.

/rantfinished

┋┊ InDesign to Kindle (& EPUB): A Professional Guide, v3.1 ┊ (Amazon) ┊┋