[wp-trac] [WordPress Trac] #55230: Release 5.9.1 breaks administration login.

WordPress Trac noreply at wordpress.org
Tue Feb 22 22:59:44 UTC 2022

#55230: Release 5.9.1 breaks administration login.
 Reporter:  carlduranleau   |      Owner:  (none)
     Type:  defect (bug)    |     Status:  new
 Priority:  normal          |  Milestone:  Awaiting Review
Component:  Administration  |    Version:  5.9.1
 Severity:  blocker         |   Keywords:  needs-patch
  Focuses:  administration  |
 The release 5.9.1 introduced a bug in script-loader.php with this new

  * Render the SVG filters supplied by theme.json.
  * Note that this doesn't render the per-block user-defined
  * filters which are handled by wp_render_duotone_support,
  * but it should be rendered before the filtered content
  * in the body to satisfy Safari's rendering quirks.
  * @since 5.9.1
 function wp_global_styles_render_svg_filters() {
          * When calling via the in_admin_header action, we only want to
 render the
          * SVGs on block editor pages.
         if (
                 is_admin() &&
                 ! get_current_screen()->is_block_editor()
         ) {

         $filters = wp_get_global_styles_svg_filters();
         if ( ! empty( $filters ) ) {
                 echo $filters;

 This method echos characters to the response stream before all "headers"
 and "cookies" have been pushed. This prevents the wp-login.php form to
 work properly because every calls to the "header" or "cookie" method then
 generates this warning: "Cannot modify header information – headers
 already sent by...”. This prevents the authentication cookie to be sent to
 the browser which breaks the authentication mechanism. To fix this issue,
 I had to add a "return;" in the new "wp_global_styles_render_svg_filters"

Ticket URL: <https://core.trac.wordpress.org/ticket/55230>
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