I see "Design N: A line is X pt: KDP needs 0.75 pt or more".

Coloring Books •1 min read •8 views •Updated Oct 1, 2026

A line on that page is thinner than KDP allows. This mostly happens on a page you edited with a fine brush. Open it in Edit and click "Thicken lines", or draw the line again with a bigger size, then save.