HTTP registry: destination_unavailable
The intermediary considers the next hop to be unavailable; e.g., recent attempts to communicate with it may have failed, or a health check may indicate that it is down.
Proxy and gateway values describe processing across trust boundaries where fields, authority, and framing may be transformed. destination_unavailable is registered in HTTP Proxy Error Types. Defining reference: rfc9209.
Identifier (http)
destination_unavailable
The intermediary considers the next hop to be unavailable; e.g., recent attempts to communicate with it may have failed, or a health check may indicate that it is down.
Strip hop-by-hop data, normalize framing, trust forwarded metadata only from configured proxies, and avoid exposing topology or credentials.
This registry value is currently marked active by IANA. Follow the defining specification before sending, accepting, or proxying it.
IANA registry: http-proxy-status/http-proxy-error-types
Registry reference: rfc9209
Sources