This topic describes the causes of errors returned with HTTP status code 203 and the solutions to these errors.


  • Error message: Callback to application server failed, please check your callbackUrl.
  • Cause: The error message returned because callback parameters are formatted or configured incorrectly. For example, upload callback can fail because the callback parameters within ArgumentValue are not in the valid JSON format.
  • Solution: See Upload callback errors and troubleshooting to find detailed solutions.