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Hi there,
novice here trying to get a book file out of indesign as an epub. But when validating the file I receive this message, can anyone help me get out of the weeds:
Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
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For the life of me, I cannot find this option to embed or not embed fonts. I choose File/Export, select reflowable EPUB, look through all the options in the dialog box, but cannot find any option to embed or not embed fonts. Yet, when I try to upload to IngramSpark, I get the same error:
(PKG-026): /META-INF/encryption.xml: Obfuscated resource must be a Font Core Media Type (was declared as "application/x-font-ttf" in "OEBPS/content.opf").
I've checked and all my fonts are otf but I'd love to not embed them at all in the EPUB if I don't have to.
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Font embedding for reflowable EPUB is controlled with a checkbox option in the export menu, under the HTML/CSS pane:
Fonts should never be embedded in reflowable EPUB; it's better yet not to have styles even spec them, but that has to be done at the CSS style level.
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Thank you for showing exactly where to "not embed" the fonts in a reflowable EPUB. I was having the exact same issue as OP when trying to upload an EPUB to IngramSpark (though Amazon KDP accepted it without a problem). Turns out, "Include Embeddable Fonts" was checked by default, and I am new, so I just never knew that, or how/where to change it. I appreciate the actual screenshot -- it helps us noobs more than I can say.
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I had this same problem and found a solution on another site:
Obfuscation can only be done on core media type fonts but you're using a non-standard media type to declare your TTF fonts. To fix the errors, change the media types of the fonts in the package document manifest from "application/x-font-ttf" to either "font/ttf" or "application/font-sfnt". Those are the only media types epub recognizes for TTF.
So, go into the content.opf file inside the EPUB and search for the manifest item(s) for your TrueType font(s). It will look something like this:
<item id="CrimsonText-Bold.ttf" href="font/CrimsonText-Bold.ttf" media-type="application/x-font-ttf" />
And then change to:
<item id="CrimsonText-Bold.ttf" href="font/CrimsonText-Bold.ttf" media-type="font/ttf" />
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This appears to have fixed the error for me! Thanks!
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Well, this is fixing things by painting over them, more or less.
First, EPUB surgery/editing is an obsolete practice. If you have to hack the exported file, you've done something wrong upstream.
Unchecking the box noted above will eliminate the embedded fonts and the problem; CSS style adjustments will take named fonts out of the picture entirely, as they should be for reflowable EPUB.
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Thank you for your knowledge! I'm having this issue this morning and unchecking that box resolved it.
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I had this error come up in IngramSpark.
I ran the ebook through Caliber, converting the epub into an epub (yes, the same file format) and it fixed the problem.
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The correct choice, though, is not to use FXL — it's an obsolete approach with many and increasing problems, and should be used only for "picture page" books like graphic novels and children's books. It should never be used for what are largely text-content books: that's what reflowable is best at.
Currently, I'm working on a sort of archival reprint art book with lots of text (basically, we're reprinting magazines). We are going with FXL because the designs are complicated and we want the reader to view the page as is, so reflowable doesn't seem to suit this book's purpose.
Right now, Courier Prime is giving me this error message because it's a TTF font—even though I installed it via Adobe Fonts. I could just download the TTF font on the original github website and convert it to OTF to resolve this issue. But out of curiosity, I have a few questions:
- The other fonts that were giving me error messages were Arial, Impact, aka the typical system fonts that come with every computer. Is this error message basically saying that there is a problem with encrypting these TTF fonts?
- On a different thread, you wrote that these validation errors are of little meaning if these EPUBs display fine. Will there be significant issues if I were to ignore the error message for Courier?
- How is it that Adobe stated that they will no longer support TTF fonts in 2023, and yet Courier Prime shows up as a TTF font? Should I be worried about the legacy of using Courier in this book?
Thanks in advance for your responses! I've seen your responses across different threads and wanted to say I appreciate them 🙂
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(Thanks.)
None of this is simple. FXL has its place when fixed page content is truly needed, but that doesn't really resolve any of its problems at either the creation or viewing end. If what you have is page images, FXL is your only good choice to display them, but (as you're finding) it doesn't support things like TOCs and live text very well. This is all compounded by InDesign's flaws at producing it. And then that's all compounded by the slow shift to better accessibility, which is an uneven movement across the standards, tools, resale vendors and readers.
Fonts — Adobe didn't deprecate TTF fonts, but T1 fonts, the very, very old font format that originated in the 1980s, IIRC. They gave years of warning about it but the change still caught quite a few legacy designers and shops by surprise.
The font fault you're seeing is that ID doesn't handle the export well and doesn't write structural code that is compliant with the shifting models. The only fixes are to switch to a modern OTF version of the font (or any common OTF font, when the face doesn't really matter), which still generates some errors but often passes the vendor validation steps. Or, edit the header code of the EPUB file, which I strongly deprecate as an outmoded approach. As you don't actually need any display text in this book, just text links for the TOC, switching to any modern (file format) font should see you clear. If the validation has changed yet again and calls out InDesign's poor management of embedded fonts... you may have to look up the header editing steps. (It's trivial, as I recall — moving the font listing from one section to another, or renaming a header section. The problem is that you have to make that edit every time you re-export the book.)