Yesterday we identified a bug in the AdWords API sandbox that results in requests returning error code 131. We are working on a fix now. In the meantime, we would like to recommend a work-around.
Developers can still work with the sandbox by using the older V4 request headers. Specifically, developers should use “token” instead of “developerToken,” and they should not include “applicationToken” in their headers.
Thank you for your patience, and we will let you know as soon as this bug is resolved.
-- Jon Diorio, Sr. Product Marketing Manager
