AWS error downloading object from S3, "profile file cannot be null"

The top voted answer by Ryan put me on the right track, but since AmazonS3Client is now deprecated, this code has resolved the problem for me

    AmazonS3 s3 = AmazonS3ClientBuilder.standard()
                  .withCredentials(DefaultAWSCredentialsProviderChain.getInstance())
                  .build();

This code appears to correctly pick up the active IAM role, say in Lambda.

It looks like you solved this in the comments, but I got burned on this and want to leave a clearer answer for future readers. To be super clear, the problem here has nothing to do with files in S3. This error message has nothing to do with the file on your hard drive nor the file that you're trying to push/pull from S3. The problem is that you're initializing S3 with something like:

AmazonS3 s3Client = new AmazonS3Client(new ProfileCredentialsProvider());

When you do that, it looks in ~/.aws/credentials for a list of profiles. This might work great on your computer but won't work anywhere that you're getting AWS access through an IAM role (ex. Lambda, Docker, EC2 instance, etc). The fix, is to initialize the AmazonS3Client like:

AmazonS3 s3Client = new AmazonS3Client();

If you're using code that requires some kind of credentials provider, you can also do:

AmazonS3 s3Client = new AmazonS3Client(DefaultAWSCredentialsProviderChain.getInstance());

Hopefully that helps the next person. In my case, I was using DynamoDB and SQS, but I had the same error. I originally ignored this question because I thought your problem was S3 related and was super confused. Wrist slapped.

On newer versions of the SDK, you'll need to use following code:

AmazonS3 s3Client = AmazonS3ClientBuilder.standard()                  
                      .withCredentials(DefaultAWSCredentialsProviderChain.getInstance())
                      .build();