Fix Undefined index

Hello,

Thank you for contacting the support and sorry for not following up quickly and any inconvenience that might have been caused due to that.

Assuming you are using the latest version of all the plugins and the themes (please update if not yet), it would seem like a conflict with one of the plugins or the theme you are using.

To determine that, please follow this troubleshooting guide:
https://rankmath.com/kb/check-plugin-conflicts/

Only the site admin would know and your users won’t be affected by this troubleshooting.

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Rank Math takes the schema data from your product pages automatically and turns it into Schema-ready content. Likewise, the aggregateRating and review fields are taken from your actual product reviews that your buyers/customers leave on your products.

If you don’t have any reviews yet, that is going to show up as a warning in the schema testing tool. That’s because Google will actually look for those fields.

Please acquire some reviews and ratings to get rid of the aggregateRating and review warnings.

You can fix the SKU and availability issue easily as well:

To fix the brand warning, head over to WordPress Dashboard > Rank Math > General Settings > WooCommerce and choose from any of the available fields to use as your product’s brands.

If you want to use a custom value for your Brands, you can do that by using the following code in your theme’s functions.php file:

// Add Brand for Products.
add_filter( 'rank_math/snippet/rich_snippet_product_entity', function( $entity ) {
$entity['brand'] = 'Rank Math;
return $entity;
});

Replace the “Rank Math” text with your actual brand name then run your website through the Structured Data Testing tool once again.

Hope that helps and please do not hesitate to let us know if you need our assistance with anything else.