Rails raises a CookieOverflow exception when the total size of the incoming request's cookie crosses a certain threshold - currently set as 4096 bytes. While it is not advisable to store or pass around such large data in cookies, sometimes, bad actors can try to send large cookie payloads to your application to see if your systems are able to handle it. If not handled, your application would end up raising a large number of 500 exceptions. This gem handles the exception gracefully and responds with a 422 Unprocessable Entity HTTP status code.