Since theExperimentService contains a fewasynchronous operations, the mechanism for fetching errors related to theseoperations is different than for other synchronous operations.

The asynchronous operations that use this error reporting mechanism are:

• ExperimentService.ScheduleExperiment
• ExperimentService.PromoteExperiment

For these methods, the API returns alongrunningoperationwhich you can use to request details on the status of the asynchronousoperation. Upon completion, the longrunning operation will populate theerrorandresponse fields. In the Google Ads API, the operation will always populate theresponse with anEmpty value, and the presence oferror will indicatethat a full list of errors can be retrieved from another API call.

If the full list of errors were returned as part of the longrunning operation,then there's a chance the errors might be lost if you don't follow up on theasynchronous progress, and the response may be larger than you might expectfrom a simple polling request. Therefore, the longrunning operation will onlyindicate that there are errors, and to fetch the specific errors you must usean API endpoint.

For errors relating to any of these experiment-based long running operations,useExperimentService.ListExperimentAsyncErrors.

Pass in the resource name of the experiment, and a page size, then page throughthe results as you would for any other Google Ads API query.