By mfb on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
9.5.x
Introduced in version: 
9.5.0
Issue links: 
https://www.drupal.org/node/3266589
Description: 

EntityViewController adds rel="canonical" and rel="shortlink" links to content entity pages. Previously these links were added as both link HTTP headers and link HTML tags, but are now added only as link HTML tags.

Before:

$ curl -s -I -X GET "http://drupal.localhost"
HTTP/1.1 200 OK
Date: Fri, 25 Feb 2022 15:43:15 GMT
Server: Apache/2.4.52 (Unix) OpenSSL/1.1.1m PHP/8.1.2
X-Content-Type-Options: nosniff
X-Powered-By: PHP/8.1.2
Cache-Control: must-revalidate, no-cache, private
X-Drupal-Dynamic-Cache: MISS
Link: <http://drupal.localhost/node/1>; rel="canonical"
Link: <http://drupal.localhost/node/1>; rel="shortlink"
X-UA-Compatible: IE=edge
Content-language: en
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Permissions-Policy: interest-cohort=()
Expires: Sun, 19 Nov 1978 05:00:00 GMT
X-Generator: Drupal 9 (https://www.drupal.org)
X-Drupal-Cache: HIT
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8

After:

$ curl -s -I -X GET "http://drupal.localhost"
HTTP/1.1 200 OK
Date: Fri, 25 Feb 2022 15:44:03 GMT
Server: Apache/2.4.52 (Unix) OpenSSL/1.1.1m PHP/8.1.2
X-Content-Type-Options: nosniff
X-Powered-By: PHP/8.1.2
Cache-Control: must-revalidate, no-cache, private
X-Drupal-Dynamic-Cache: MISS
X-UA-Compatible: IE=edge
Content-language: en
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Permissions-Policy: interest-cohort=()
Expires: Sun, 19 Nov 1978 05:00:00 GMT
X-Generator: Drupal 9 (https://www.drupal.org)
X-Drupal-Cache: HIT
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8
Impacts: 
Site builders, administrators, editors