Google are very specific in their requirements for the information that you provide in your product feed. If you don't meet them, then they are liable to reject your feed. There are a number of areas where stores tend to fall down. The purpose of this article is to provide a simple checklist for the things that you need to take care of to prevent this from happening.
This article is specifically written for the benefit of e-commerce store owners using our GooglebaseXML extension for Virtuemart, however much of the information applies more generally.
1) Firstly, check your images. Google will not accept products that do not include images. For Joomla sites there is a specific issue that normally arises with the robots.txt file that is distributed with Joomla, because it restricts access to the images folder so Google cannot crawl it. To fix this you will need to remove the line:
Disallow: /images/
There is a more in-depth discuss of images here.
2) Check that you have provided a valid value for the Google product category. This is what tells Google which category your products fall into according to their own taxonomy, so is very important in telling them where to display your products. If you don't they may well reject your feed. The Google product taxonomy is available here. You must choose a value taken from the taxonomy, don't just make up a category of your own. Examples are:-
Animals & Pet Supplies > Pet Supplies > Dog Supplies
Clothing & Accessories > Shoes > Outdoor Shoes
Note that you must include the entire category tree, NOT
Dog Supplies
Outdoor Shoes
How to supply this value? Our GoogebaseXML extension includes an option 'Default Google Category'. For many specialist stores all the products may be covered by a single category, so it will be enough to past the relevant value from Google's product taxonomy into this option. If your products fall into a variety of categories you will need to supply this value using a Virtuemart custom field. This is described in more detail in our documentation.
3) Check that you have provided a valid GTIN for your products. This must be a valid UPC or EAN barcode number. Do not just make up a number, Google will know and will reject it. If you do not have GTIN for your products, firstly make a real effort to find them out. GTINS are used to provide a unique classification system for products, so can only be issued by specific bodies with the power to issue them, normally you will need to purchase them from one of these bodies if they do not already exist, you cannot just make them up.
If they do not exist at all, and you cannot obtain them, then turn on the 'Use Identifier Exists Tag' in the GooglebaseXML options, this will send a special tag to Google when neither the GTIN nor MPN exist.
GooglebaseXML includes an option to use the product sku for the GTIN. You should only use this if the SKU is a valid GTIN - some sites use the barcode number as an SKU, so can use this option, otherwise you should not.
4) Check that you have provided a valid MPN for your products. This must be a valid manufacturer part number, do not just make up a number - unless of course you are the manufacturer, in which case you can supply the number that you normally use to identify the part. If no MPN exists for your products, for example for one-off products, then turn on the 'Use Identifier Exists Tag' in the GooglebaseXML options, this will send a special tag to Google when neither the GTIN nor MPN exist.
GooglebaseXML includes an option to use the product sku for the MPN. You should only use this if the SKU is a valid MPN - some sites use the MPN as an SKU, so can use this option, otherwise you should not. For example if you are a manufacturer then the value that you use for the SKU could properly be considered to be the MPN, as it is simply the number that a manufacturer uses to identify a part.
5) Check that you have supplied the brand of your products. Google use this, along with the GTIN and MPN to try and uniquely identify your products. GooglebaseXML includes several options for this, including to set a default value for the brand (useful if all your products have the same brand); use your own product category value (eg if you sell products from several brands and categorize them by brand on your site); use the manufacturer value; or use a custom field value.
6) Check that your site meets Google's terms and conditions, for example don't use promotional text in your product names or images, make sure that your prices are clearly visible.
7) Additional Things to Check. Google publishes information about its product feed specification here, it is well worth reading it thoroughly.
You have submitted your feed to Google and are still getting errors, what do you do? Read the error message carefully, they are generally informative. Fix the issue, and re-submit your feed to Google. It will probably take some time for them to notice that you have fixed the problems, so if you are confident that you have done so, don't panic if you continue to see the error message for a while. Normally it just requires waiting, sometimes Google will need to re-crawl your site, which can take a few days.