426
Upgrade Required
Client errors (4xx)·RFC 9110
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.