AppLovin SDKs return errors as integer codes, but to make this more manageable, there are a set of named constants that correspond to these codes. This gives you the flexibility to check for errors using the named constants.

Here is an Android example:

public void failedToReceiveAd(int errorCode) {
  if(errorCode == MaxErrorCode.NO_FILL){
      // Indicates that no ads are currently eligible for your device & location.
  }
  else{
      // Unable to reach AppLovin; the user's device is likely experiencing poor connectivity.
  }
}

If you check for the specific error returned, AppLovin recommends that you use these named constants rather than the integers in your code. For a list of these error codes and constants, see Android > Overview > Error Codes in the MAX Integration Guide.