That was actually a fun read, and if we lived in a just society, Adobe would be forced to care about making shitty software. But alas.

At least there's some easy workarounds.

Something i have been foing for years in calibre is saving the de-drm version of all ebooks that i bought. And getting the txt version of the files.

The ebook format is basically a subset of html if you ever look into it. And as time goes on ebook readers have different ways to show these books. Most of the time, its great! Sometimes its not. Give it another 50 years and we will see what works and what doesnt. But i garentee at least the txt files will still work.

I didnt know what authors and publishers go though. Thanks for that lemmydividebyzero

Could this be solved by having two renderers, and only using the proprietary Adobe one needed?

So what do you do when the pedantic gold standard of epubcheck says your book is fine, when it works without issue on Amazon Kindle, Apple Books, Thorium and everywhere else and yet Kobo says it’s “corrupted”?

I dug into this matter and found out that Kobo uses RMSDK, “Reader Mobile Software Development Kit”, Adobe’s proprietary ebook rendering engine.

Once the stylesheet was identified as the source of my woes, I could finally drill down to find which specific line was causing the issue. After creating a dozen more variations with different subsets of my stylesheet I eventually identified the culprit. It was this line:

.copyright img {
    max-width: min(150px, 30vw);
}

Once I changed it to the more old fashioned max-width: 150px; ADE opened it just fine.

But what is the problem here? The above code is perfectly valid CSS level 4, it’s just not supported by RMSDK, because its CSS parser is frozen in approximately 2013 — no flexbox, no grid, no math functions, no custom properties. Just good old float, bad font handling, and silent crashes when it sees anything it doesn’t recognize.

It’s the year 2026. Thanks to the horrendous RMSDK which Kobo decided to use as their backbone for all book rendering (probably for DRM reasons), a single line of perfectly valid CSS turns a perfectly valid EPUB file into a “corrupted file” on Kobo and just drops the whole book. No clear error message, no fallback. Just a massive fail.

First thing I've done after buying kobo installed koreader on it.

We tell stories of all that was lost in the library of Alexandria.

Do people have suggestions other than Kobo for a color ereader? I am trying to avoid feeling too locked down/in and thought Kobo was that. I'm still rocking an old nook I got for a few bucks at a thrift store years ago. I was led to believe Kobo was the most open option while still having access to local libraries.

I read most the article. Having been in print in the past I remember how PDFs are the primary document format the world over. And that it got so big that Adobe licenses off the format to a legal firm that manages it for them. I remember there being something about a PDF2 format being implemented behind the scenes that most people aren't aware of.

PDF2 is capable of a lot more and is more efficient. However most of that increased capability is used for control and monitoring.

this is a great article, actually. i didn't realize what a process it was for compatibility between devices.

and damn adobe is annoying.