426 Upgrade Required

Look up a status, pick the right one for an API, or hit a live endpoint that actually returns it. Add ?code=418 to this URL and the response is that status — useful for curl, interceptors, and “what does my client do on 503?” Nothing here phones home except the Try it fetch to this same page.

Which class?

426

Upgrade Required

Client error · RFC 9110

The client should switch protocols as named in Upgrade (for example, TLS or HTTP/2).

When to use

Requiring HTTPS or a newer HTTP version.

Don’t

Not for deprecating an API version — use 410 or 400 with a body.

Live URL

curl -i https://corecoding.com/utilities/http-status.php?code=426


    

Code use cases