4xx Client error responses
426Upgrade Required
Protocol upgrade required
#When does this occur?
Returned when the server refuses to process the request with the current protocol and requires an upgrade. (e.g., upgrade to HTTPS required)
#How to handle?
Upgrade to the protocol specified in the Upgrade header. Usually, switching to HTTPS will work.
#Example
HTTP Response
HTTP/1.1 426 Upgrade Required
Content-Type: application/json
Date: Tue, 10 Feb 2026 07:17:19 GMT
{
"status": 426,
"message": "Upgrade Required"
}#Related Status Codes
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