If you own a Kindle e-reader from 2012 or earlier, you need to update its software by March 22, 2016, or else your device will lose Internet connectivity.
The ominous-sounding update won't be a huge problem for most users, as Kindles normally update themselves when connected to the Internet. However, users who have an older model lying around, switched off or disconnected from the net, should make sure this critical update has been installed.
Devices affected are Kindle Paperwhite 5th generation from 2012, Kindle DX 2nd generation from 2009, and Kindle Keyboard 3rd generation from 2010. Regular Kindles, generations 1, 2, 3 and 4, from 2007, 2009, 2011 and 2012, also need to be updated.
Newer models don't require this update.
To make sure your Kindle has been updated, go to your Kindle's Menu from the Home screen and choose "Sync and Check for Items." Check out this post by Amazon for detailed instructions on how to update your Kindle and determine which software it's running for each of the variants mentioned above.
If you don't update your device by March 22, you'll likely see the following message: "Your Kindle is unable to connect at this time. Please make sure you are within wireless range and try again. If the problem persists, please restart your Kindle from the Menu in Settings and try again."
Don't worry, though: You can still update your Kindle manually. You can find instructions on how to do so on this page.