Note to anyone involving themselves in ebook publishing: do NOT use smart quotes or any other form of auto - formatting. (madgeniusclub.com)
Pressque editors default to curved quotes known as smart quotes, rather than straight quotation marks that are known as non-smart quotations. (blog.infinitypublishing.com)
If you're trying to take your description all the way to 399 or 400 characters, you may get this error, because if you're copying and pasting your description from Word, and you have smart (curly) quotes enabled, then a cut - and - pasted smart quote counts as more than one character. (smashwords.com)