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    HTTP Status Codes
    These HTTP status codes can appear during payer authentication. 
- 201: AUTHENTICATION_FAILED
 - Encountered a payer authentication problem. Payer could not be authenticated.
 - 201: CONSUMER_AUTHENTICATIION_REQUIRED
 - Encountered a payer authentication problem. Payer could not be authenticated.
 - 400: CONSUMER_AUTHENTICATIION_FAILED
 - Encountered a payer authentication problem. Payer could not be authenticated.
 - 400: INVALID_DATA
 - Declined: One or more fields in the request contain invalid data.
 - 400: INVALID_MERCHANT_CONFIGURATION
 - Declined: There is a problem with your merchant configuration.
 - 400: MISSING_FIELD
 - Declined: The request is missing one or more fields.
 - 502: SYSTEM_ERROR
 - Error: General system failure. A system error occurred.
 - 502: SYSTEM_TIMEOUT
 - Error: The request was received but a server timeout occurred. This error does not include timeouts between the client and the server.
 - 502: SYSTEM_TIMEOUT
 - Error: The request was received, but a service did not finish running in time.