As previously mentioned, the production environment will start requiring developer tokens with report downloads starting on Tuesday, January 17th. Please see the original blog post for details regarding how to provide the token and what errors you will see when it is not provided.

The sandbox environment has required the developer token as an HTTP header since November 16th. We strongly encourage you to test your production report download code against the sandbox environment to confirm that you will not experience any disruptions in report downloads. The AdWords API client libraries have also been updated to reflect this change; upgrade to the newest version of your client library to ensure continued reporting.

If you have any questions or would like to discuss these changes, please post on the forum or attend one of the AdWords API Office Hours Hangouts.