407 Proxy Authentication Required

Like 401, but a proxy is asking for credentials, in a Proxy-Authenticate header.

Class
4xx Client Error. The request has a fault, or cannot be met as sent.
Registered
Yes, in the IANA HTTP status code registry.
Cacheable by default
No. A cache stores it only when Cache-Control or Expires says to.
References
RFC 9110 ยง15.5.8 · MDN

Example response

HTTP/1.1 407 Proxy Authentication Required
Proxy-Authenticate: Basic realm="proxy"

Every 4xx code

All HTTP status codes, in one table