Missing field SKU for variable product

Hello,

Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.

You can fix the SKU and availability issue by applying the SKU code here:

If your schema data is not updating then it seems like an issue with the caching. However, you have stated already that you are not using cache on your site. Please contact your site host if they are using server-side caching. Purging the site cache should fix this issue.

Looking forward to helping you. Thank you.

Hello,

I logged into your staging website’s admin area and upon investigating, I found that you only added the SKU to the variations of the product and left the main SKU field empty. You can have a look at the screenshot in the sensitive data section of this ticket.

We only add the main SKU of the product to the schema since for variable products, the only required property by Google is the price:
https://developers.google.com/search/docs/advanced/structured-data/product

I added a demo SKU to the main SKU field of the product and then tested using Google’s Rich Results testing tool and the SKU warning was removed. I’ve added a screencast in the sensitive data section of this ticket.

Hope this helps.

Thank you.

Hello,

As price is the only required property for variable products, we haven’t included SKUs of the variable products in the schema.

Also, directly adding multiple SKUs in the product schema would make the schema invalid.

You can add the SKU of the first/default variation of the product in the main SKU field.

Hope this helps.

Thank you.

Hello,

I tried to access your staging website but it is returning a connection timed out error. Here’s a screenshot: https://i.rankmath.com/aitjBh

Please try adding the below code to the website and see if the SKU of the variable products are added to the schema:

add_filter( 'rank_math/snippet/rich_snippet_product_entity', function( $entity ) {
	if ( ! is_product() ) {
		return $entity;
	}

	$product = wc_get_product( get_the_ID() );
	if ( ! $product->is_type( 'variable' ) ) {
		return $entity;
	}

	$variations = $product->get_available_variations();
	if ( ! empty( $variations ) ) {
		$offers = [];
		foreach ( $variations as $variation ) {
			$price_valid_until = get_post_meta( $variation['variation_id'], '_sale_price_dates_to', true );
			$offers[] = [
				'@type'           => 'Offer',
				'description'     => strip_tags( $variation['variation_description'] ),
				'price'           => $variation['display_price'],
				'priceCurrency'   => get_woocommerce_currency(),
				'availability'    => $variation['is_in_stock'] ? 'https://schema.org/InStock' : 'https://schema.org/OutOfStock',
				'itemCondition'   => 'NewCondition',
				'priceValidUntil' => $price_valid_until ? date_i18n( 'Y-m-d', $price_valid_until ) : '2025-12-31',
				'url'             => $product->get_permalink(),
                                'sku'             => $variation['sku'],
			];
		}
	}

	$entity['offers'] = $offers;

	return $entity;
} );

Let us know how that goes.

Thank you.