Dynamodb aws Invalid Argument Exception

I have been stuck on this for a few days now and any help would be great.

I am trying to data from CSV files into Dynamodb with the SDK for PHP. I am reading from a CSV file and writing the records into the database using batchwriteto insert the records. I am inserting everything as a string. It inserts about 4000 records and then gives me the following error:

PHP Fatal error:  Uncaught exception 
'Guzzle\Common\Exception\InvalidArgumentException' with message 'Invalid 
resource type' in /home/ubuntu/aws-php-
sample/vendor/guzzle/guzzle/src/Guzzle/Http/EntityBody.php:50

What does this error mean, and why am I getting this?

Is it because those set of records I am attempting to insert have some characters that are not accepted by dynamo?