I'm on 2.3.7 and when I uploaded to Amazon I used Android Studio to generate the APK file. But if it worked for you then that's great. I was mainly informing you about the date of the post you responded to.
2.3.7 is beta. I do not use beta versions for publishing exports as they are not 'stable.' When you check 2.3.6 you'll see the only Eclipse support when export for Amazon. Android Studio is used for Google Play exports in that version. Yes, I know it's old post, but it's somehow relevant today, as I am getting the same errors.