HTTP PRI

The registered PRI request method from the IANA HTTP Method Registry.

PRI is safe and idempotent according to the IANA registry. Use it only when the target protocol defines its semantics and the intermediary chain supports it.

httpmethodssafeidempotentregistry

Request (http)

PRI * HTTP/2.0

PRI is a registered extension method rather than a general browser/API default. Its registry properties describe the intended effect, not whether every implementation supports it.

PRI is not an ordinary request method: it appears only as the fixed HTTP/2 client connection preface ("PRI * HTTP/2.0") that starts every HTTP/2 connection, and servers must reject PRI used anywhere else.

Common mistakes

Assuming registration means that browsers, proxies, frameworks, or APIs support the method automatically.
Sending PRI as a normal application request method.

Registry reference: rfc9113

Sources

IANA HTTP Method Registry
RFC 9110: HTTP Semantics