A few months back I posted about an ongoing problem affecting some Kindles that’s causing them to suddenly delete all sideloaded content under certain circumstances.
Nobody seems to know what the exact cause is, and it’s been going on for a long time now. I keep seeing people posting about the disappearing books bug on various platforms, and none of Amazon’s software updates seem to fix the problem.
It doesn’t appear to be a widespread issue but enough people are being affected by it that it keeps coming up regularly, and almost all reports seem to have two things in common.
Most people that encounter the disappearing ebooks issue say they used Calibre to load the ebooks onto their Kindle, and their Kindle was in airplane mode for an extended period of time after loading the ebooks onto it. Then after turning airplane mode off and connecting their Kindle to WiFi they find all their sideload books have suddenly disappeared.
These types of reports usually include comments from other people saying they also use Calibre to sideload books on their Kindle, but they have not experienced this problem, and most of those people say they tend to leave WiFi turned on most of time.
Given that, it seems to be an issue related to keeping airplane mode on for an extended amount of time. How long that is exactly, who knows, but at this point if you use Calibre to sideload books onto your Kindle you’re probably better off keeping WiFi turned on all the time or off all the time if you don’t want to encounter the random disappearing books bug.
It also goes without saying you should keep backups of all the books you add to your Kindle in case something like this happens, but most people using Calibre are doing that already.
Hopefully Amazon will get this problem sorted out soon. Kindles randomly deleting sideloaded content isn’t a good look and it could turn into some really bad publicity, especially if they continue to do nothing about it.