Debugging

Work down this list in order. Most filter issues come from one of the first three steps.

1. Enable WordPress Debug Mode

Add these lines to wp-config.php:

define( 'WP_DEBUG', true );
define( 'WP_DEBUG_LOG', true );
define( 'WP_DEBUG_DISPLAY', false );

PHP notices, warnings, and fatal errors are written to wp-content/debug.log. Leave WP_DEBUG_DISPLAY off on a live store - you do not want raw PHP errors in front of shoppers.

2. Check the Log

Look at the tail of wp-content/debug.log. Filter-related messages mention the plugin’s text domain, wb-ajax-filter, or its class names. Every fatal error logs the file and line that caused it.

3. Check the Browser Console

1. Open developer tools (F12).
2. Console tab - look for JavaScript errors and failed network requests.
3. Network tab - filter by wb-ajax to see the AJAX filter calls; a red row means the request failed.

4. Test a Clean Setup

• Deactivate other plugins - filter conflicts first. Keep only Ajax Filter and WooCommerce, then re-enable the rest one by one.
• Switch to a default theme - a theme that does not fire woocommerce_before_shop_loop (typically a block theme) will not auto-render filters; place them with the block or shortcode instead.
• Clear caches - page cache, object cache, and CDN. A stale cache looks exactly like “my filters do not work”.

5. Confirm WooCommerce Is Active

The plugin self-deactivates if WooCommerce is not active - you would already have seen the banner, but a half-started restructure can leave the plugin inactive with old cache still serving.

6. Test the REST API Isolating

Hit the endpoint directly to separate the API from the frontend:

curl -u "storemanager:xxxx xxxx xxxx xxxx xxxx xxxx" \
  "https://your-site.com/wp-json/wb-ajax-filter/v1/presets?per_page=5"

A 401/403 means the credentials or role are the problem. An empty array with 200 and X-WP-Total: 0 means there are simply no presets (see Common Issues).

Related Pages

• Common Issues - the usual fixes for each symptom.