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---
title: 426 Upgrade Required
slug: Web/HTTP/Status/426
page-type: http-status-code
spec-urls: https://httpwg.org/specs/rfc9110.html#status.426
---
{{HTTPSidebar}}
The HTTP **`426 Upgrade Required`** client error response code
indicates that 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 sends an {{HTTPHeader("Upgrade")}} header with this response to indicate the
required protocol(s).
## Status
```http
426 Upgrade Required
```
## Examples
```http
HTTP/1.1 426 Upgrade Required
Upgrade: HTTP/2.0
Connection: Upgrade
Content-Length: 53
Content-Type: text/plain
This service requires use of the HTTP/2.0 protocol
```
## Specifications
{{Specifications}}
## See also
- {{HTTPHeader("Upgrade")}}
- {{HTTPStatus("101")}} `Switching Protocols`