Why are my facets not working after updating to WP 6.9?

Some users are experiencing non-functional facets and a JSON error in the browser console after updating to WordPress 6.9.

We are actively investigating what triggers this issue exactly. It is caused by WP’s new template enhancement output buffer that conflicts with FacetWP’s output buffering in some situations, depending on other installed plugins.

For now, you can fix this issue by adding the following snippet to your (child) theme’s functions.php. The snippet disables the new template enhancement buffer in WP 6.9 during FacetWP’s AJAX refresh.

How to use custom PHP code?
PHP code can be added to your (child) theme's functions.php file. Alternatively, you can use the Custom Hooks add-on, or a code snippets plugin. More info
<?php
// Disables the new template enhancement buffer in WP 6.9 during FacetWP's AJAX refresh
add_filter( 'wp_should_output_buffer_template_for_enhancement', function( $should ) {
  if ( function_exists( 'FWP' ) && FWP()->request && FWP()->request->is_refresh ) {
    return false;
  }
  return $should;
} );

Note that other plugins, like Elementor, are experiencing similar issues, and have disabled this new feature in their latest version or have issued a fix. So make sure to update all your plugins when updating to WP6.9.

See also

• Using FacetWP with Elementor