What Is a 426 Status Code?

The server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol.

The server MUST send an Upgrade header field in a 426 response to indicate the required protocol(s)1.

Example:

HTTP/1.1 426 Upgrade Required
Upgrade: HTTP/3.0
Connection: Upgrade
Content-Length: 53
Content-Type: text/plain

This service requires use of the HTTP/3.0 protocol.

426 CODE REFERENCES

Rails HTTP Status Symbol :upgrade_required

Symfony HTTP Status Constant Response::HTTP_UPGRADE_REQUIRED

Additional resources


Return to List of HTTP Status Codes

TO TOP