Getting 'Error 431: Request Header Fields Too Large' – How Do I Fix This? or What Causes Error 431 an

Lol, error 431 is like the internet’s way of saying "TL;DR" to your headers.

For Firefox users: Go to `about:config` and tweak `network.http.max-response-header-size` (but be careful—don’t break stuff).

Also, some ad blockers or privacy tools (like Privacy Badger) can accidentally inflate headers. Disable ‘em and see.