Starting Feb 15, 2019, in all AdWords API versions and in the Google Ads API, we’re going to reject requests that attempt to create a Smart Shopping campaign with the local inventory ads setting enabled. The local inventory ads setting is equivalent to setting enableLocal to true in the AdWords API, and enable_local to true in the Google Ads API. Trying to set those fields to true when creating a Smart Shopping campaign will result in the OperationAccessDenied.OPERATION_NOT_PERMITTED_FOR_CAMPAIGN_TYPE error. Previously, those fields were ignored when passed to the API servers.

Why is this happening?
Throwing an error for the requests described above provides an alert to users that local inventory ads are not supported in Smart Shopping campaigns.

What should you do?
Make sure you do not have code that creates a Smart Shopping campaign with local inventory ads enabled. Specifically, when you create a ShoppingSetting object for a Smart Shopping campaign, take either of the following actions:

• (Preferable) Do not set enableLocal (AdWords API) or enable_local (Google Ads API) at all
• Set enableLocal (AdWords API) or enable_local (Google Ads API) to false

Follow the guides below for details on how to create a Smart Shopping campaign:

• AdWords API
• Google Ads API

As always, if you have any questions or concerns, please post them on our forum.
 - Thanet Praneenararat, Google Ads API Team

Source: Google Ads Developer Blog