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If you are using Timber, with the Timber Library plugin, and you are seeing an intermittent “FacetWP was unable to auto-detect the post listing” error, the likely cause is Timber caching.

To quickly fix this, or to test if this is the cause, you can entirely disable Timber caching by adding the following snippet to your (child) theme’s functions.php:

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
add_filter('timber/cache/mode', function () {
  return Timber\Loader::CACHE_NONE;
});

This snippet uses the timber/cache/mode filter to set the Timber cache mode to CACHE_NONE. The default cache mode is CACHE_TRANSIENT, which we have seen causing the described issue.

We have not tested this, but CACHE_OBJECT cache mode likely causes similar issues, because object caching in general is often problematic with FacetWP.

Note that Timber caching will be automatically enabled if you use a non-false value in the $expires argument of the Timber::render() function.

If you want to disable Timber caching only for your pages with facets, you can do something like in the following snippet. Add the page IDs of your facet pages to the array in line 5.

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
define( 'TIMBER_CACHE_TIME', 3600 ); // To set a global $expires

$timber_cache_mode = Timber\Loader::CACHE_USE_DEFAULT;

$facetwp_page_ids = [10213, 20218]; // The page IDs of your pages with facets

$request_post_id = 0;

if ( isset( $timber_post_obj->ID ) ) {
  $request_post_id = (int) $timber_post_obj->ID;
}

if ( in_array( $request_post_id, $facetwp_page_ids, true ) ) {
  $timber_cache_mode = Timber\Loader::CACHE_NONE;
}

Timber::render( 'page-builder.twig', $context, TIMBER_CACHE_TIME, $timber_cache_mode );

Possible WP Engine connection

So far, we’ve seen the above Timber caching issue only when using WP Engine.

With WP Engine using memcached for the transients API, and Timber caching using the default CACHE_TRANSIENT mode, this seems a probable connection. However, after testing, it seems unlikely that WP Engine is involved because the issue also happens with WP Engine’s object caching disabled (as recommended), which means memcached logically cannot be involved.

We don’t know the internals of WP Engine caching, so there is no definitive conclusion about WP Engine involvement. Please let us know if you’ve encountered these issues and have more info, so we can document it for other users.

See also

Last updated: June 4, 2026