We removed the PrimaryUserLogin column from all our reports in AdWords API v201406. To keep the rest of our API consistent, we will also remove the login field from ManagedCustomer class in the next AdWords API release. Existing versions of the AdWords API will stop returning values for this field starting November 5, 2014.

If you’re currently using the login field to identify an account, you can use the customerId or name field instead. The AdWords API uses OAuth 2.0 as its authentication mechanism, which allows users to grant access to your application to manage their AdWords accounts, without sharing their email addresses.

To ensure your applications continue to work properly, stop using this field before November 5, 2014. If you have any further questions about this change, let us know via our forum or Google+ page.