KDP Error: The trim size I chose does not match the file I submitted

This error indicates that your book incorporates elements (such as a Full Page Image or a Heading Background) that call for a Full Bleed layout. When using Full Bleed, your PDF will be made slightly larger to include a bleed region.

To address this error, you’ll need to indicate to KDP that you’re using Full Bleed. You can do that by selecting Bleed in the Print Options section of your book’s setup at KDP: