HP. Stones

QualityCheck Plugin Hack (Stop Amazon deleting your books)

Last update: 2025 / 08 / 30
taken from a rentry.co page on mobileraeds, for archival purposes

Reports suggest that some Kindles delete all books sideloaded to a device after prolonged use of Airplane Mode due to an internal label bug. When the Kindle reconnects to Wifi, it checks whether you've purchased a book. Since the device confuses itself in this process, it decides to nuke all your books.

Other reports suggest that changing an internal label on those books from EBOK to PDOC may circumvent this problem.

The problem lays mostly in Calibre's part, as it still tags sideloaded books as EBOK, and it still doesn't offer a way to change it for AZW3 sideloaded books, you have to tag them as PDOC manually.

If you're using KFX or MOBI for your sidelaoded books, you might want to skip to the FAQ.

  1. Download and install the QualityCheck plugin from Calibre
  2. Go to your calibre plugins folder ()
  3. Unzip the qualitycheck.zip plugin as a folder
  4. Search for a file named check_fix.py
  5. Modify the following lines:
  mu.update(asin, b'EBOK')

to...

  mu.update(asin, b'PDOC')
  1. Save changes, select all the files inside the folder and zip them back in. Do not just zip the folder, that will just make a zip with a singular folder inside and it will not be detected as a plugin on Calibre
  2. Replace the old QualityCheck.zip
  3. In calibre, convert any book to AZW3
  4. Open the QualityCheck plugin > Fix > Fix ASIN for Kindle Fire.
  5. Your AZW3 book is now a PDOC.

You can use a metadata viewer to see if the book is actually a PDOC.

FAQ

But I use MOBI/KFX. What do I do?

MOBI files by default are set to PDOC, I am not sure about this, but you can check this on Calibre Preferences > Output Options > MOBI.

For KFX books (you can convert books as KFX by installing KFX Output plugin), you can tell Calibre to always tag converted books as PDOC. (Calibre Preferences > Output Options > KFX Output > "Create personal document").

Is this method safe? Will something happen to my Kindle?

Yes it is safe, nothing bad will happen to your Kindle. There haven't been reports of PDOC tagged books being nuked so far, here is one report claiming their PDOC tags weren’t nuked.

But why not just use Send To Kindle? isn't that easier?

Maybe.