Why do I see an “HTTP 431” error?

If you see an “HTTP 431” error on your site, it indicates that your web browser is sending much larger than normal “headers” to the server.

In most cases, the large data turns out to be old, unused cookies that your browser has stored. To fix this, try “clearing the cookies” in your web browser for your site.

(You can also try using a different web browser that probably won’t have so many cookies set.)