Can you spot the error in the text?

Any copy that your business presents to the world (web content, blog posts, news releases, white papers, emails, tweets, captions, etc.) must be perfect. Your customers expect no less. Many forms of marketing and advertising are subjective — some people will like it, some won’t. However, the rules of grammar always apply. There are no exceptions.

I have extensive experience as a copyeditor.
Be sure your copy is flawless; hire an editor.

P.S. pfft … there’s no error.