Most rejections are arguments about measurements. This one is simpler: a locked PDF is a door KDP’s systems are not allowed to open. The review process needs to read, measure, convert, and eventually print your file — every one of those operations is exactly what PDF security settings exist to restrict — so the platform’s policy is not “unlock it for us” but “don’t submit it locked.”
What KDP is actually saying
The rule appears in KDP’s published PDF submission guidelines under its own heading, “Security Encrypted File”:
- “Security encrypted or locked files prevent us from completing our file review process.”
- “All security should be removed from a file before submitting.”
KDP’s print publishing guidelines carry the same sentence in slightly harder words — security-encrypted or locked files “prevent us from publishing your paperback.” Two distinctions decide whether your file is legal. First, an open password (needed to view the file at all) and a permissions password (the file opens, but printing/copying/editing are restricted) are both “security” — the second is the sneaky one, because the file looks perfectly normal while you’re reading it. Second, this is about the uploaded file, entirely separate from Kindle ebook DRM, which is a store setting and never applies to print PDFs.
| How the lock got in | The tell |
|---|---|
| Word: “Encrypt with Password” or Restrict Editing, set during drafting and never removed | File asks for a password, or opens read-only |
| A designer sent a “protected” client-proof PDF and it was uploaded as-is | Properties show an owner/permissions password |
| Online PDF compressors / “protect” tools applied security by default | The file came back from a free web tool |
| Print-shop or school/office PDF policies adding permissions automatically | Security method shows “Password Security” in Acrobat |
Check it yourself
- Acrobat/Reader: File > Properties > Security tab. The only passing result is Security Method: No Security. Anything else — “Password Security,” restricted printing, restricted copying — is a locked file for KDP’s purposes.
- The padlock tell: a lock icon in the reader’s sidebar or title area means document restrictions are active, even when the file opens without asking for anything.
- Check both files. Interior and cover are reviewed separately; a clean interior doesn’t rescue a locked cover.
- Check the delivered file, not your memory of it. If any tool touched the PDF after your clean export — a compressor, a merger, an email-security gateway — verify again on the exact file you upload.
Want both files verified end to end? The free check reads your actual interior and cover PDFs — security settings, fonts, layers, geometry, barcode zone — and reports every finding in plain English, free within 48 hours. Get the free check →
How to fix it
The principle
Never “crack” the submitted file — go back to the unlocked source and export a clean PDF. Unlocking tools produce files of uncertain structure; a fresh export from Word, InDesign, Canva, or Pages is never encrypted unless you ask it to be.
In Word
Open the document, then File > Info > Protect Document: clear “Encrypt with Password” (enter the password, save with it blank) and remove any Restrict Editing. Export the PDF afterwards — the full settings are in our Word export guide. Note that “Mark as Final” is only a flag, not encryption, but remove it anyway.
From a designer or a tool
Ask for the deliverable as “print PDF, no security, no password.” If the only copy you hold is a permissions-locked proof and you know the owner password, Acrobat (File > Properties > Security > No Security) removes it legitimately; if you don’t know it, the source files are the only route.
The honest limit
There is one dead end and we won’t pretend otherwise: if the only surviving copy of the book is inside a PDF whose password is lost, KDP can’t accept it and no legitimate service can rebuild it from the locked file — the book has to be re-created from whatever sources remain (drafts, printouts, the ebook edition). Keep your sources, export clean, and this rejection becomes the easiest one in the library to never see again: one glance at the Security tab.
Or send us the files — the check is free
Email your interior and cover PDFs and we'll tell you exactly what's wrong — in plain English, free, within 48 hours. If it does need fixing, the by-hand fix is $19 and we redo it free if KDP rejects it for a formatting issue we were hired to fix. We rebuild files to be compliant with KDP's published spec — that's the promise we can keep.
Prefer the whole library in one file? The KDP Rejection Field Guide (free PDF) collects every guide, table, and the 13-point checklist.
More from the Help Library
- The KDP & IngramSpark Help Library — all guides & tools
- PDF layers & annotations — comments, form fields, live layers
- Transparency error — flattened files, shifted colors
- “Manuscript has errors” — the generic error, decoded
- Fonts are not embedded — how to check and fix
- Word → KDP: the two settings that prevent the classic Word rejections
- The free rejection check — all 13 checks at once