https://stackoverflow.com/a/11013986
I would not suggest Richies answer, because you are screwing up the data inside the database. You would not fix your problem but try to "hide" it and not being able to perform essential database operations with the crapped data.
If you encounter this error either the data you are sending is not UTF-8 encoded, or your connection is not UTF-8. First, verify, that the data source (a file, ...) really is UTF-8.
Then, check your database connection, you should do this after connecting:
SET NAMES 'utf8'; SET CHARACTER SET utf8;