If you have a Kindle that was purchased in 2012 or earlier and you want to keep using it to access new books, you need to install a critical update no later than TODAY. (Otherwise it will be more difficult to update in future.)
Details on installing the update can be found here.
Would it be snarky to mention that paper books don’t need to be upgraded? Probably.
Please take a moment to support Amazing Stories with a one-time or recurring donation via Patreon. We rely on donations to keep the site going, and we need your financial support to continue quality coverage of the science fiction, fantasy, and horror genres as well as supply free stories weekly for your reading pleasure.
https://www.patreon.com/amazingstoriesmag