If you are using ECS 3.2.0.0, this is a known bug with Multi-part uploads.

The fix will be in v3.2.0.1, which should be released 22-May.

Normal uploads will work as will multi-part uploads if the URL is not percent-encoded. For 3.2.0.0, the work-around is to avoid using percent-encoding in multi-part uploads.

ok thanks. I'll wait for v3.2.0.1.

"For 3.2.0.0, the work-around is to avoid using percent-encoding in multi-part uploads."

-- But I am using ip and port directly like to create AmazonS3 client.

EndpointConfiguration endpointConfiguration = new EndpointConfiguration("*.*.*.*:9021", "US_WEST_2");

Which URL should be percent-encoded?

I'm talking about the URL that is the MPU request. For instance:

POST /Bucket1/object.name?uploads

It is common to percent-encode the 'dot' in the URL above:

POST /Bucket1/object%2Ename?uploads

If the URL does contain a percent-encoded character (such as the %2E above), the MPU will fail until you upgrade to ECS 3.2.0.1.

Yes but I am doing using aws-java-sdk-s3  and not through rest url and my keyname and bucketName doesn't contain any special characters. As said before that It works for me without .withSSECustomerKey(SSE_KEY) but with server side encryption S3_CLIENT.uploadPart fails 

Your original note stated that the upload failed as a multi-part, but worked as a single upload. In BOTH cases you were using withSSECustomerKey(SSE_KEY). It never states that you were successful without "withSSECustomerKey(SSE_KEY)"

From reading the bug report, there should be no association of this error with SSE. Please verify this behavior, and be careful that any request that has no percent-encoded will cause the multi-part upload to succeed.

my bad if post is misinterpreted . I meant uploadpart is successful without "withSSECustomerKey(SSE_KEY)". I have tried it number of times but upload part is continuously failing with withSSECustomerKey(SSE_KEY). I am not sure whether withSSECustomerKey(SSE_KEY) introduces any percent-encoded due to encryption but same request is passing without withSSECustomerKey(SSE_KEY).

Since you are using the AWS SDK, you have access to the TransferManager class.  Using this to upload MPU with SSE-C against ECS Test Drive (ECS v3.2.0) works for me.  Here is my code excerpt:

        // Create an encryption key.
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        keyGenerator.init(256, new SecureRandom());
        SSECustomerKey encKey = new SSECustomerKey(keyGenerator.generateKey());

        ObjectMetadata metadata = new ObjectMetadata();
        metadata.setContentLength(data.length);

        // only way to use SSE-C is to use a POR:
        PutObjectRequest putRequest = new PutObjectRequest(testBucket, key, dataStream, metadata);
        putRequest.withSSECustomerKey(encKey);

        // set MPU threshold to 1 to make sure we use MPU
        TransferManager tm = TransferManagerBuilder.standard().withS3Client(client).withMultipartUploadThreshold(1L).build();
        tm.upload(putRequest).waitForUploadResult();

But how will TransferManager work with UploadPartRequest object for I don't have single stream but each part is coming as seperate stream of length say 5MB each. Is there something we can do similar to com.emc.vipr.services.s3.model.AppendObjectRequest or com.emc.vipr.services.s3.model.UpdateObjectRequest in com.emc.vipr s3-client package for aws-s3-sdk as well for ViPRS3Client doesn't work with  withSSECustomerKey

The current code is

 long partSize = 5 * 1024 * 1024; // Set part size to 5 MB.
 // Create a list of ETag objects. You retrieve ETags for each object part
 // uploaded,
 // then, after each individual part has been uploaded, pass the list of ETags to
 // the request to complete the upload.
 List
    partETags = new ArrayList
    ();
    
   


 ObjectMetadata objectMetadata = new ObjectMetadata();
 // objectMetadata.setContentType("application/x-www-form-urlencoded;
 // charset=utf-8");
 objectMetadata.setContentLength(contentLength);


 objectMetadata.setSSEAlgorithm(ObjectMetadata.AES_256_SERVER_SIDE_ENCRYPTION);


 // Initiate the multipart upload.
 InitiateMultipartUploadRequest initRequest = new InitiateMultipartUploadRequest(bucketName, keyName,
 objectMetadata);
 InitiateMultipartUploadResult initResponse = S3_CLIENT.initiateMultipartUpload(initRequest);


 // Upload the file parts.
 long filePosition = 0;
 for (int i = 1; filePosition < contentLength; i++) {
 // Because the last part could be less than 5 MB, adjust the part size as
 // needed.
 partSize = Math.min(partSize, (contentLength - filePosition));


 byte[] subArray = Arrays.copyOfRange(contentBytes, (int) filePosition, (int) (filePosition + partSize));


 // Create the request to upload a part.
 UploadPartRequest uploadRequest = new UploadPartRequest()// .withSSECustomerKey(SSE_KEY)
 .withBucketName(bucketName).withKey(keyName).withUploadId(initResponse.getUploadId())
 .withPartNumber(i).withInputStream(new ByteArrayInputStream(subArray)).withPartSize(partSize)
 .withSSECustomerKey(SSE_KEY);//works without withSSECustomerKey
//but fails with Unable to execute HTTP request: Connection reset by peer: socket write error for withSSECustomerKey

 boolean isError = false;
 while (!isError) {
 try {
 // Upload the part and add the response's ETag to our list.
 UploadPartResult uploadResult = S3_CLIENT.uploadPart(uploadRequest);
 partETags.add(uploadResult.getPartETag());
 } catch (Exception e) {
 System.out.println(e.getMessage());
 continue;
 }
 System.out.println("done upload part");
 isError = true;
 }
 filePosition += partSize;
 }


 // Complete the multipart upload.
 CompleteMultipartUploadRequest compRequest = new CompleteMultipartUploadRequest(bucketName, keyName,
 initResponse.getUploadId(), partETags);
 S3_CLIENT.completeMultipartUpload(compRequest);

Thanks for pointing out the mistake that I was doing. I was doing objectMetadata.setSSEAlgorithm(ObjectMetadata.AES_256_SERVER_SIDE_ENCRYPTION); and then passing it to initRequest but going by suggestion to use

1. initRequest.setSSECustomerKey(SSE_KEY); // ADD THIS LINE and removing objectMetadata.setSSEAlgorithm(ObjectMetadata.AES_256_SERVER_SIDE_ENCRYPTION);

worked for me and I am able to upload file successfully using UploadPartRequest with .withSSECustomerKey(SSE_KEY) attached screenshot. thanks for quick suggestions.