What causes http error 431 and how do I resolve it?

[Freya]

I saw http error 431 while loading a site what does that mean (headers too large?), and what steps can I try (clear cookies, reduce header size, try incognito, check proxies) to fix it quickly?

 

[rebeccareed]

HTTP Error 431 basically means the browser is sending too many or too large headers. Most of the time it’s just corrupted cookies from that specific site. The quickest fix is: clear cookies for that site → refresh. If you don’t want to log out, open an Incognito tab and test. If it loads there, it’s definitely a cookie/header issue. Rarely, it's the server misconfigured, but 90% it's your browser.

 

[megamind]

Bro same thing happened to me last week on a shopping site. Turned out I had like 200 cookies stored from that domain . I just cleared cookies for that one site and boom working again. Try incognito mode first though, it’s easier and you won’t lose your logins.

 

[ethanwalker]

431 is almost always on the server, not the browser. People keep saying “clear cookies”, but if the server expects smaller headers, that’s on them.

 

[jimmy]

Nah man, that’s not true. 431 literally gets triggered because your local browser sends bloated cookies. Clearing them fixes it for most users. I work in web dev trust me.

 

[ethanwalker]

Alright Mr. Web Dev, but explain why it worked fine after the site updated then?

 

[Emmawoods]

I swear this error only shows up at the worst time. I got it right when I was trying to pay my bill. Cleared cookies → site logged me out → completely forgot my password → now I'm in a bigger problem than 431 itself

 

[AngelinaFi]

Try these in order:

1. Incognito window
2. Clear cookies for that website
3. Disable VPN/Proxy
4. Restart browser

If none of this works, the site probably has messed-up header limits. Then all you can do is wait for them to fix it.

 

[joetribounii]

Nope, that is not the case. The 431 response is literally set off by the transfer of oversized cookies from your local browser. Removing such cookies solves the problem for a large number of users. I am a web developer so you can put your trust in me.