Kindle Direct Publishing (KDP) can be both a cute adorable bunny one day, and then a raging dragon the next, so take a deep breath, let it out, and look through the error messages noted below to see if you can locate the one the fire-breather is currently throwing at you.
These mainly focus on the book cover upload portion, but if you receive other error messages, toss them in the comments and I’ll add them, and the solution, to this post as well.
Error message: Adjust the design of your cover to accommodate a barcode size of 2″ (50.8 mm) by 1.2″ (30.5 mm) tall that does not overlap with another barcode.
Solution: Your designer has included the barcode on the back cover. Therefore, in the “Book Cover” section on KDP where you “upload a cover you already have (print-ready PDF only)”, there is a small box that needs to be checked that says “Check this box if the cover you’re uploading includes a barcode. If you don’t check the box, we’ll add a barcode for you.” Screenshot below.