426 Upgrade Required
Switch to a different protocol to continue.
What it means
The Upgrade header names the required protocol, for example TLS or HTTP/2.
What your client should do
Use the protocol named in Upgrade.
Should you retry?
Only after you change the request.
Try it
The free practice API returns this status on demand, with the headers a well-behaved API would send. Call GET /api/play/status/426 from Endpoint Client and open the Explain tab.
Defined in RFC 9110. All status codes and headers