As we previously announced, we began enforcement of the new unique product identifier feed specification as part of an ongoing effort to improve product data quality on Google Shopping. These new specifications help us serve better results to our users while creating more opportunities for merchants.

Enforcement of these new specifications has begun and will continue to ramp up over the coming weeks. By September, all violating offers will be rejected and will not be served through Product Listing Ads.

These new feed specifications will affect all accounts in the United States and non-exempt accounts in France, Germany, and the United Kingdom. Beginning September 16th, all previously exempt accounts in France, Germany, and the United Kingdom as well as all other targeted countries will be subject to these new requirements.Google Shopping Product Feeds: Unique Product Identifier Specification Ramps Up [adwords.blogspot.com]