KDP says my cover dimensions are wrong. What should I check?

KDP checks that your cover exactly matches the book's required wrap size. If it complains, check these in order:

1. Page count. The most common cause by far. Your spine width is built from the page count you entered in the Cover Maker — if it doesn't match the interior you're uploading, the whole wrap is the wrong width. Set the cover's page count to your final interior page count and re-export. See Why does the cover maker need my page count?
2. Printer profile. Make sure the cover was exported for KDP, not IngramSpark — their wrap math differs.
3. Trim size. The cover's trim must match the interior's trim (both 6×9, both 5.5×8.5, etc.).
4. Binding. A paperback wrap and a hardcover case wrap are different sizes — confirm you exported the binding you're actually publishing.

Fix the mismatch, re-export, and re-upload. If the interior length changed at any point, that's almost certainly it — see Can I change the page count after exporting?