[enuddleyarbl]

I don't know if this is a problem with Calibre 6.5.0 or with the book (it's C.S. Friedman's "When True Night Falls"). But, when I convert a book to EPUB3 (either from the library page or from within the editor), I get this when trying to open it:

calibre, version 6.5.0
ERROR: Failed to open book: Failed to open book, it has obfuscated fonts, but the obfuscation key is missing from the OPF. Do an EPUB to EPUB conversion before trying to edit this book.

If I Add the AZW3 from Amazon, I can open it in the Calibre editor without problem. Under the Fonts section, there are two red-shielded fonts (00068.otf and 00069.otf). There's no encryption.xml type file under the Miscellaneous section. The only thing font related in metadata.opf that I can see is:

<manifest>
    <item id="id1" href="fonts/00068.otf" media-type="font/otf"/>
    <item id="id2" href="fonts/00069.otf" media-type="font/otf"/>

If I right-click the AZW3 and tell Calibre to convert it (individually) to EPUB2, I can open the epub in the editor without problem. The two red-shielded fonts are still there and the encryption.xml is now under Miscellaneous. It contains:

<encryption
                    xmlns="urn:oasis:names:tc:opendocument:xmlns:container"
                    xmlns:enc="http://www.w3.org/2001/04/xmlenc#"
                    xmlns:deenc="http://ns.adobe.com/digitaleditions/enc">
                    
                <enc:EncryptedData>
                    <enc:EncryptionMethod Algorithm="http://ns.adobe.com/pdf/enc#RC"/>
                    <enc:CipherData>
                    <enc:CipherReference URI="fonts/00068.otf"/>
                    </enc:CipherData>
                </enc:EncryptedData>
                

                <enc:EncryptedData>
                    <enc:EncryptionMethod Algorithm="http://ns.adobe.com/pdf/enc#RC"/>
                    <enc:CipherData>
                    <enc:CipherReference URI="fonts/00069.otf"/>
                    </enc:CipherData>
                </enc:EncryptedData>
                
</encryption>

The fonts are still listed in content.opf, but look slightly different:

<item id="id1" href="fonts/00068.otf" media-type="application/vnd.ms-opentype"/>
    <item id="id2" href="fonts/00069.otf" media-type="application/vnd.ms-opentype"/>

The Calibre viewer will happily view either the AZW3 or the EPUB2 (and I've read the book before on both a Kindle and a Kobo Forma).

If I convert from that EPUB2 to an EPUB3 in the editor and look at the changes (before closing the editor down and re-opening it), the only instances of "font" are those same two unchanged font lines in content.opf.

Once I save, shut down the editor and re-open the epub (as an EPUB3), I get that same error message. Worse, I can't see any of the content/files in the epub.

If I run the epub through the Modify ePub PI and have it Remove Embedded Fonts, I can once again edit the book, and all the contents are there. The fonts are gone (obviously), but the encryption.xml is still there (and looks the same) and the fonts are missing from the content.opf (again, obviously).

Doing conversions like this in the previous Calibre version went fine. Is there something else I can check or post here?

EDIT: I was hoping I could check this with the previous book in the series, since I edited under Calibre 6.4.0 without problem. But, it has no fonts (and converts just fine). I'll have to look around and see if I can find any other books with embedded fonts and see how they convert under 6.5.0.

EDIT2: Still haven't found another book with fonts. But, I redownloaded this book fresh from Amazon and got the same behavior. Are those fonts supposed to have a red shield on them? Does that indicate a problem or does it indicate that the fonts are encrypted?