Specification of the HTTP status code 426

The 426 Upgrade Required status 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 MUST send an Upgrade header field in a 426 Upgrade Required response to indicate the required protocol(s) (Section 6.7 of [RFC7230]).

Example:

HTTP/1.1 426 Upgrade Required Upgrade Required
Upgrade: HTTP/3.0
Connection: Upgrade
Content-Length: 53
Content-Type: text/plain

This service requires use of the HTTP/3.0 protocol.

Source / Quote by: The 426 Upgrade Required HTTP Status Code is specified by section 6.5.15 of RFC7231.

HTTP-Protocol

HTTP/1.1 (1999)

HTTP/2 (2022)

HTTP/3 (2022)

How to throw a 426 statuscode with PHP?

To throw the HTTP status code 426 on a web page, the PHP function http_response_code can be used. The syntax is as follows: http_response_code(426) (PHP 5 >= 5.4.0, PHP 7, PHP 8)

Test the 426 HTTP status code

http-statuscode.com (Test Status code 426)

httpstat.us (Test Status code 426)

In order to be able to display the HTTP status code (in this case 426 Upgrade Required) and other information on the client side, the development console must be opened with F12. Afterwards you have to navigate to the tab "Network". Now you can open the page, in the network tab you should see the web page (example index.php). This must be selected and then the Herder section must be selected. Here the user will see the following result:

Overview
URL: https://http-statuscode.com/errorCodeExample.php?code=426
Status: 426 Upgrade Required
Those: Network
IP address: XX.XX.XX.XX

How to create a custom error page for the 426 status code

Creating your own 426 Upgrade Required error page is relatively easy with the web server "Apache" as well as with the web server "NGINX".

Apache Webserver

The web server "Apache" is one of the most popular web servers on the Internet. To create an own 426 Upgrade Required error page in "Apache", the following change must be made in the following file.

File: .htaccess

ErrorDocument 426 /errors/426.html

NGINX Webserver

Similar to the web server "Apache", "NGINX" is also widely used on the Internet. To create your own 426 Upgrade Required error page in "NGINX", the following change must be made in the following file.

File: sites-enabled/default

error_page 426 /426.html;
location = /426.html {
root /usr/share/nginx/html;
internal;
}

Browser compatibility of the 426 status code

Chrome	no data
Edge	no data
Firefox	no data
Opera	no data
Safari	no data
Chrome Android	no data
Firefox for Android	no data
Opera Android	no data
Safari on iOS	no data
Internet	no data
WebView Android	no data