Hey all.

I posted this on the Kindle developers forum, but perhaps it would be of more interest here. Mods, please feel free to remove as you see fit.

I received this notification from KDP Customer Support today:

Have I misunderstood, or does this put an end to the "dual mobi" approach described in this thread?
I'm hoping this means that no more Mobi. Mobi should have gone away a long time ago.
Big news.

When you publish a reflowable book on Amazon using a MOBI or DOCX file Amazon converts it to all of the formats supported by old and new Kindle devices/apps. There is no need to publish using a "dual MOBI" (aka Master MOBI) to achieve that effect.
If Amazon will no longer allow me to upload the MOBI file that is created by KindleGen/Kindle Previewer, then how do I get the backwards compatibility to KF7 described by Tex2002ans here?

My concern is that, as Hitch says here, there are millions of older devices still out there, and they cannot read KF8.
Simply upload valid epubs. Amazon will automatically generate books suitable for older devices.
Dual mobi is only for Smashwords or your own use.

The mobi format has been depreciated for UPLOADS years ago. The epub2 is recommended.

This has only ONE effect on Amazon customers. Newer Kindles may get more advanced formatting than possible from mobi uploads to KDP. Older Kindles will still get mobi/KF7 downloads.

AFAIK Amazon doesn't deliver dual mobi to customers.

What Doitsu says.

So this is hardly news. Amazon no longer accepts an upload format that no-one should be using and they recommended alternatives years ago.

Oodles of free and paid tools convert wordprocessor content to epub2.
There is no sign that the elimination of the book delivery formats needed to support older Kindle devices is driving this change or is even a goal of Amazon.

I believe that this change is a step toward making all reflowable books published in the future available in the newer KFX format.
This is what I'm thinking too.

Probably wanted to slowly phase out the "Dual MOBI"/ancient formats + push their new KFX format.

Also making sure people who are updating older ebooks are now following more modern code/standards.

Yep, that's also what I'm thinking.

So you could either:

1 (Best). Upload EPUB.

Amazon will generate all the files (KF7+KF8+KFX) for you.

2. Upload KPF (just like you would the "Dual MOBI").

Amazon will generate (KF7+KFX) for you.

Exactly. Seems to me it's just simplifying the input.

(Although I wish Amazon were more open... would be interesting to see exactly how much garbage they get. What % of ebooks coming in are still PRC/AZK/Calibre-converted-MOBI, etc.)

I'm betting they've been spending a ton on customer support dealing with the confusion around "Dual MOBI" as well.

And as was discussed last year in those linked threads... there's a whole bunch of nonsense about MOBI floating around online too. This KPF push probably lets them get rid of a decade+ of baggage.
So if author/publisher uploads KPF, there will be no KF8 available to readers? If readers go to Amazon website and "download for transfer via USB" they will get KF7?


Yes, I believe that's correct.

I think I recall jhowell explaining it in detail in one of those threads a few months ago. See his Post #3 in "ebook in KFX and old-mobi - no KF8".

(Although that was a KPF out of Kindle Create. Unsure if that still holds for a KPF out of the new Kindle Previewer.)