AWS machine learning prediction schema problems
I ran into the same problem today, tried googling for people having the same issue and found your question.

I solved my problem by creating the data source first and then running the prediction from there. So, instead of selecting the following option,

Batch Predictions &gt; Create new batch prediction &gt; ML model for batch prediction &gt; My data is in S3, and I need to create a datasource

which fails, I first did:

Datasources &gt; Create a new datasource... 

Next, I ran the batch prediction from an existing datasource successfully.