HTTP 426 Upgrade Required

Client Error

The server refuses to process the request using the current protocol. The client must upgrade to a different protocol.

Common Causes

Server requires HTTPS instead of HTTP
Server requires HTTP/2 or WebSocket upgrade

How to Fix

Switch to the protocol indicated in the Upgrade header
Use HTTPS if the server requires it

Related Status Codes

101 Switching Protocols 301 Moved Permanently

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