SVCS
426

Upgrade Required

Client errors (4xx)·RFC 9110

HTTP 426 Upgrade Required is a Client errors (4xx) status code. The client should switch to a different protocol given in the Upgrade header.

What 426 means

The client should switch to a different protocol given in the Upgrade header.

For example, requiring TLS or a newer HTTP version before the request can be served.

Client errors (4xx)

The request contains an error from the client — bad syntax, missing auth or a wrong URL.

Other 4xx codes

400Bad Request401Unauthorized402Payment Required403Forbidden404Not Found405Method Not Allowed406Not Acceptable407Proxy Authentication Required408Request Timeout409Conflict410Gone411Length Required412Precondition Failed413Content Too Large414URI Too Long415Unsupported Media Type416Range Not Satisfiable417Expectation Failed418I'm a teapot421Misdirected Request422Unprocessable Content423Locked424Failed Dependency425Too Early428Precondition Required429Too Many Requests431Request Header Fields Too Large451Unavailable For Legal Reasons

FAQ — 426

What does HTTP 426 mean?

426 Upgrade Required: The client should switch to a different protocol given in the Upgrade header. For example, requiring TLS or a newer HTTP version before the request can be served.

Which class does status code 426 belong to?

426 is a Client errors (4xx) code. The request contains an error from the client — bad syntax, missing auth or a wrong URL.

Where is the 426 code defined?

Status code 426 is defined in RFC 9110 and is part of the IANA HTTP Status Code Registry.

← All HTTP status codes