header_value_too_large

HTTP 431 · code header_value_too_large · limit MaxHeaderValueBytes

One header value is longer than the server accepts.

When Photon sends it

Sent before routing when a single header value exceeds MaxHeaderValueBytes (8 KiB by default). The message names the header but never echoes its value.

What the client should do

Shorten the named header, typically an oversized cookie or token.

What the server owner can do

Raise MaxHeaderValueBytes in photon.Limits if legitimate tokens are larger.

Example response

{
  "type": "https://photon.agenticmarket.dev/errors/header_value_too_large",
  "title": "header too large",
  "status": 431,
  "code": "header_value_too_large",
  "limit": "MaxHeaderValueBytes"
}

Match on the code field rather than on title, which is meant for people and may change. See all error codes.