Starting on September 14th, 2016, Productstatuses will return all the errors and warnings present in the Diagnostics tab of Merchant Center. To explain the changes, first we separate errors and warnings for products into two categories:

• Validation issues are reported as a result of product insertion and update, and they include issues such as missing required fields or invalid item IDs.
• Data quality issues are reported later after either automatic or manual review of the data provided to Merchant Center, and they include issues such as product images being too generic or a non-matching price on the landing page.

Historically, only data quality issues were available from Productstatuses, while validation issues required the developer to check the returned status from the insertion or update of the product. After this change, developers can retrieve both data quality and validation issues using Productstatuses, but this means that developers may see more issues returned by Productstatuses than before.

Please note that the includeInvalidInsertedItems URL parameter to Productstatuses.list still defaults to false. This means that, by default, calls only retrieve products which had no validation errors, and thus the retrieved products will only include data quality issues and validation warnings (if any). If you want to retrieve information about products with validation errors, please set this parameter to true.

If you have any questions or feedback about the changes to issue reporting or other questions about the Content API for Shopping, please let us know on the forum.

-Stevie Strickland, Content API for Shopping Team

Source: Google Ads Developer Blog