KDP error guide
Check transparency before print
Identify transparency and optional-content structures that may need source-level review.
Technically reviewed · September 1, 2026
What this issue means
Flattening can change appearance, so it is not automatically safe. BookPreflight reports evidence and directs risky cases back to the source application instead of silently rasterizing pages.
What BookPreflight checks
- Transparency groups and optional-content layers
- Pages and regions containing those structures
- Whether a visual comparison is required
How to correct the source file
- 1
Inspect the page in the authoring application.
- 2
Use a print PDF preset appropriate to the workflow.
- 3
Compare the exported page visually before replacing the original.
Verify the exported PDF, not the preset name
Keep the editable source and original PDF. Export a new file, run the complete scan again and review every remaining finding. A repair is only labelled safe after loss checks and a full deterministic post-flight.
BookPreflight is an independent tool. It is not affiliated with or endorsed by Amazon or Kindle Direct Publishing, and it cannot guarantee acceptance.