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

Ugh, error 431 is the worst! Had this happen to me last week. Turns out it’s usually a server-side thing, but sometimes browser extensions can bloat your headers.

Try disabling ALL extensions temporarily—just to test. If it works, re-enable one by one to find the culprit.

Also, some sites have strict header limits. If it’s just one site giving you grief, might be worth contacting their support.