Trying to make job working AWS MediaConvert (ERROR 1040)
I got this exact same error. I had to add the Audio Selectors. See the following JSON example:

"Inputs": [
  {
    "AudioSelectors": {
      "Audio Selector 1": {
        "Offset": 0,
        "DefaultSelection": "DEFAULT",
        "SelectorType": "LANGUAGE_CODE",
        "ProgramSelection": 1,
        "LanguageCode": "ENM"
      }
    },


If you are using the Java SDK, add something similar to the following to your inputs:

AudioSelector audioSelector = new AudioSelector()
            .withOffset(0)
            .withDefaultSelection("DEFAULT")
            .withLanguageCode("ENM")
            .withSelectorType("LANGUAGE_CODE")
            .withProgramSelection(1);

audioSelectors.put("Audio Selector 1", audioSelector);