What is the cause of google adwords API OpportunityError.RPC_ERROR

The documentation of the BulkOpportunityService Oppurtunity Error is found here without any helpful descriptions

http://code.google.com/apis/adwords/docs/referenc开发者_StackOverflow中文版e/latest/BulkOpportunityService.OpportunityError.html

Opportunity.Reason documentation for the two possible exceptions is found here

http://code.google.com/apis/adwords/docs/reference/latest/BulkOpportunityService.OpportunityError.Reason.html

Enumerations

1. OPPORTUNITY_DOES_NOT_EXIST
2. RPC_ERROR

Does anyone know what causes this error?

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This error indicates that there was a temporary issue with the backend for the service, and retrying later should resolve the problem.

P.S. - The best place to post questions about the AdWords API is to the official developer forum: http://code.google.com/apis/adwords/forum.html