Upgrade your 
AdWords API and 
Google Ads API ads to use 
ExpandedDynamicSearchAd (
EXPANDED_DYNAMIC_SEARCH_AD) instead of 
DynamicSearchAd (
DYNAMIC_SEARCH_AD) 
by March 6, 2019. After March 6th, creating these ads through the APIs will fail with an 
AdGroupAdError.CANNOT_CREATE_DEPRECATED_ADS error, while updating them will result in an 
AdError.CANNOT_MODIFY_AD error. Existing 
DynamicSearchAds will continue to serve.
An 
ExpandedDynamicSearchAd goes beyond automating just headlines and adds the advantage of automating display URLs, so that the subdomain of your ad matches the subdomain of your landing page. In addition, Google Ads will add a path when it expects the path to outperform a plain URL. In order to increase the performance for all our advertisers, Google Ads is moving everyone to the newer format.
If you have any questions while upgrading, please reach out to us on our 
forum.
 Nadine Sundquist, Google Ads API Team
 Nadine Sundquist, Google Ads API Team