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steve_4231
Participant
November 14, 2024
Answered

Help with font validation error when exporting to .epub

  • November 14, 2024
  • 2 replies
  • 1463 views

I'm uploading an .epub file to IngramSpark and—on the surface—everything looks to be fine. However, I'm served with this error message (three times) from IS:

(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 assume this is in relation to the 3x fonts I'm using in the .indd file – however, they are all Times New Roman (Regular, Italics and Bold styles) so there shouldn't be a licensing issue. They are .ttf files so I'm assuming that's the issue, but how do I go about rectifying that?

    Correct answer Laura Brady

    This is a dumb error that's not really an error at all. Basically EPUB Checker doesn't like TTF fonts. You can fix this by changing the media type in the OPF on thost true type fonts.

    Change it from: media-type="application/x-font-ttf"

    to: media-type="application/vnd.ms-opentype"

    I hope that helps.

    2 replies

    James Gifford—NitroPress
    James Gifford—NitroPress
    Legend
    November 14, 2024

    Don't embed fonts for reflowable EPUB. It's an obsolete practice.

     

    (As is editing generated EPUBs; if you have to perform surgery on it, you didn't generate it right. 🙂 )

    L
    Laura Brady
    Inspiring
    November 14, 2024

    That's bananas, James. Developers should embed fonts as they see fit, of course. The end user may change the typeface, but that's their perogative. 

    And if you aren't editing the EPUBs you create from InDesign, they you aren't paying attention to accessibility or clean code. 

    James Gifford—NitroPress
    James Gifford—NitroPress
    Legend
    November 14, 2024

    Sorry. We come at the field from wholly different perspectives, and mine is that of professional publication — which among other things does not include the notion that "anything a designer wants to do is fine." That doesn't apply in print or any other area of book/publication design, and it doesn't apply in digital publication either.

     

    And embedding fonts like Times Roman is just... ridiculous. Bad enough when it "has" to be some fantasy or high-art font, but whitebread, vanilla fonts? Just file bloat and technical complications, besides the fundamental rule — to me — of not respecting the medium.

     

    I haven't edited an EPUB in a decade. It is absolute not a necessary or (any longer) useful step; the correct approach is to get the document and export optimal for export in the first place.

    L
    Laura BradyCorrect answer
    Inspiring
    November 14, 2024

    This is a dumb error that's not really an error at all. Basically EPUB Checker doesn't like TTF fonts. You can fix this by changing the media type in the OPF on thost true type fonts.

    Change it from: media-type="application/x-font-ttf"

    to: media-type="application/vnd.ms-opentype"

    I hope that helps.

    J
    jenniferl_writer
    Participating Frequently
    April 30, 2025

    Thanks Laura! I have taken out the two offending fonts. Draft2Digital is very fussy, and after three hours I still have four errors. No way you could just "export to ePub reflowable" and have it work first time!

    J
    jenniferl_writer
    Participating Frequently
    April 30, 2025

    Update - finally passed the epub check! Last ones were wrong 'property' and meta property codes in content.opf. 

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