Error in Epub - indesign I have received back from my team and don't understand

Report · Feb 21, 2024

Hi,

I have an issue with a fixed layout epub, my team reported back to me this error when trying to upload it. This is a first time that it has popped up and I don't know what it means. Has anyone ever had this and how can I fix it?

" PKG-026: Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").META-INF/encryption.xml L5 META-INF/encryption.xml L23 "

screenshot here :

Report · Feb 21, 2024

Have you tried Google??

https://code-interactive.com/2023/04/obfuscated-resource-must-be-a-font-core-media-type-error-from-i...

Report · Feb 21, 2024

You have a bad font — bad for EPUB embedding/encryption. There are few solutions except replacing it with a font that is compatible/licensed for e-book export.

Report · Nov 12, 2024

It is not a bad font; it's related to the media type and is easily fixed.

Report · Nov 12, 2024

Bad as in "not compatible with the format, process or goal." It may well be technically perfect, but not within the narrow range of type, format, model or licensing EPUB demands.

Report · May 22, 2025

Hi Laura,
I'm getting a similar error in Draft2Digital's validator - there's 7 like this:
ERROR(PKG-026): /META-INF/encryption.xml(47,56): Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf")
Another 'easy fix' I'm hoping ... ?
Can you recommend someone who can help with this?
Thanks 🙂
DS

Report · May 22, 2025

Hello DS. Can you email it to me? I will record a short video of how to fix it using open-source software so you are armed for this problem in the future.

Report · May 22, 2025

Wow Laura, that was quick, thank you! 🙂
Email the book?
It's kinda big, 36mb - gmail says it will attach as a Google Drive link, no
clue how that works.
Is there something more convenient for you?
6Apr15-GBTOptimized-FixedLayout.epub
<>
--
Duke Sharp

Report · May 22, 2025

@duke_0123

If you share through Google Drive - your approval might be needed.

Or you can use DropBox.

Report · May 22, 2025

Hi Laura,
I tried your email address, got this:

Your message wasn't delivered to --------------- because the domain bradytypesettting dot com
I'm at ---------------------
I really appreciate your help - I can be kind of a klutz with 'digital communication' ...
DS

Report · May 22, 2025

I sent you an email that you can just respond to. Check your spam if you don't see it.

Report · Nov 11, 2024

I had this problem when I tried to upload the ebook to IngramSpark.

Using Calibre, I converted the epub into an epub (yes, the same file format) and that fixed the problem.

Report · Nov 12, 2024

This is an interesting approach, and of course in line with the routines for fixing corrupted InDesign and Word files. It depends, however, on the reliability of Calibre to write/rewrite code, not only for technical compliance but preserving anything outside standard, vanilla layout. I'd see it as more of a bandaid/hack than a proper approach, that of finding the actual cause of the fault and fixing it.

(I profess to be a bit baffled by the "e-book conversion" boffins. When format conversion isn't something verging on piracy, it seems unnecessary to me to convert the same book to read on different readers... but it is or was quite the active segment of the reader/collector/hacker area of the field.)

Report · Nov 12, 2024

I actually think (in my case) the problem is IngramSpark's.

We have a professional ebook converter (and I used to convert ebooks in the day when they were written in code from scratch).

The ebook uploads fine on Amazon KDP, and various ebook readers (like Kindle, iBooks, Calbre's own reader) have no problem withit. (iBook's is actually a good test of coding -- if there's a problem, it'll complain as you're going through the book on the page with the issue.) But IngramSpark flagged it.

In the past, I've found IngramSpark flag things that these other platforms don't. Also, often it flags things that are redundant, e.g. a tag that's not closed in the code, even though that has no bearing on how the ebook functions.

Interestingly, when I went into Calbre's ebook editor and used its automated fix, it broke more things as far as IngramSpark were concerned, e.g. whereas IngramSpark flagged three things previously, now it was flagging twelve.

But using Calibre's converter (converting it from epub to epub) fixed it for uploading on IngramSpark.

I'm guessing the conversion is just embedding the font in a way that's satisfying IngramSpark's internal evaluation.

Report · Nov 12, 2024

Yes, Ingram often seems to be the most stringent vendor, more or less in step with every warning and info report EPUBcheck generates, but unforgiving about any of them.

The real solution here is not to embed fonts in EPUB. It brings little to most books, it's wholly dependent on reader and user choices anyway, it bloats file sizes and — all too often — it simply brings more convoluted trouble than any jot of esthetic improvement.

To me, it's part of "respect the medium" to not try to force print-like control on e-books. If you're obsessed with presenting a page 'just so' — use PDF.

Report · Nov 12, 2024

This is a known issue and is related to TTF fonts. When you export from InDesign they come out with "application/x-font-ttf" in the manifest. If you change that to "application/vnd.ms-opentype" your fonts will still work just fine and you won't have a validation error.

Report · Jan 24, 2025

I've just encountered this problem with a book I've tried to upload to IS for a client. How do I go about changing the above when exporting from InDesign to EPUB?

Report · Jan 24, 2025

It's not possible from InDesign. Fixing this requires you to go into the EPUB code to manually fix the font type.

Report · Jan 24, 2025

Thank you Laura, bit out of my skills / comfort zone at this time but I'm sure I can sort it out.

Report · Jan 24, 2025

The fundamental fix is to change to a font compatible with EPUB export; it can even be "the same font" but of a more modern and compliant format. The export and validation process for EPUB is less and less tolerant of older formats, especially those from secondary sources that may not have been well-constructed in the first place.

Report · Jan 24, 2025

So Adobe fonts are not going to work in this instance?

Report · Jan 24, 2025

Adobe fonts are fine. They aren't the issue.

Report · Jan 24, 2025

That's not the issue here, James. TTF fonts are perfectly acceptable fonts to embed in an EPUB. The problem is that some versions of EPUB Checker, including the one that Ingram Spark uses, are marking TTF fonts types as an error when they aren't. It's flagged as an error for the developers to fix but until then, the workaround is to change the media type in the OPF of the EPUB to read "vnd.ms-opentype".

Report · Apr 11, 2025

Hi,

Can you please guide me how to change the media type as I am finding it difficult. Thank you so much in advance.

Report · Apr 11, 2025

Hi,

Can you please guide me step by step how can I change the media type in the OPF?

Thank you so much!