AWS S3 GetObject: Unable to Unmarshall Response (null)

Question

I'm trying to download files from an S3 Bucket using the Java SDK v2. I'm able to successfully upload and list objects in the bucket, but when I try to download the previously uploaded objects, I get the error stacktrace listed below. I've checked the bucket contents via the UI, and the objects are all in place and aren't null objects either. Please advise.

This is the code snippet for getting objects:

GetObjectRequest getRequest = GetObjectRequest.builder()
                                              .bucket(bucketName)
                                              .key(objKey)
                                              .build();
s3.getObject(getRequest, 
ResponseTransformer.toFile(Paths.get(fileName)));

And this is the error stacktrace:

software.amazon.awssdk.core.exception.SdkClientException: Unable to unmarshall response (null). Response Code: 200, Response Text: OK
at software.amazon.awssdk.core.exception.SdkClientException$BuilderImpl.build(SdkClientException.java:97)
at software.amazon.awssdk.core.internal.http.pipeline.stages.HandleResponseStage.handleSuccessResponse(HandleResponseStage.java:100)
at software.amazon.awssdk.core.internal.http.pipeline.stages.HandleResponseStage.handleResponse(HandleResponseStage.java:70)
at software.amazon.awssdk.core.internal.http.pipeline.stages.HandleResponseStage.execute(HandleResponseStage.java:58)
at software.amazon.awssdk.core.internal.http.pipeline.stages.HandleResponseStage.execute(HandleResponseStage.java:41)
at software.amazon.awssdk.core.internal.http.pipeline.RequestPipelineBuilder$ComposingRequestPipelineStage.execute(RequestPipelineBuilder.java:206)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ApiCallAttemptTimeoutTrackingStage.execute(ApiCallAttemptTimeoutTrackingStage.java:64)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ApiCallAttemptTimeoutTrackingStage.execute(ApiCallAttemptTimeoutTrackingStage.java:36)
at software.amazon.awssdk.core.internal.http.pipeline.stages.TimeoutExceptionHandlingStage.execute(TimeoutExceptionHandlingStage.java:77)
at software.amazon.awssdk.core.internal.http.pipeline.stages.TimeoutExceptionHandlingStage.execute(TimeoutExceptionHandlingStage.java:39)
at software.amazon.awssdk.core.internal.http.pipeline.stages.RetryableStage$RetryExecutor.doExecute(RetryableStage.java:113)
at software.amazon.awssdk.core.internal.http.pipeline.stages.RetryableStage$RetryExecutor.execute(RetryableStage.java:86)
at software.amazon.awssdk.core.internal.http.pipeline.stages.RetryableStage.execute(RetryableStage.java:62)
at software.amazon.awssdk.core.internal.http.pipeline.stages.RetryableStage.execute(RetryableStage.java:42)
at software.amazon.awssdk.core.internal.http.pipeline.RequestPipelineBuilder$ComposingRequestPipelineStage.execute(RequestPipelineBuilder.java:206)
at software.amazon.awssdk.core.internal.http.StreamManagingStage.execute(StreamManagingStage.java:57)
at software.amazon.awssdk.core.internal.http.StreamManagingStage.execute(StreamManagingStage.java:37)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ApiCallTimeoutTrackingStage.executeWithTimer(ApiCallTimeoutTrackingStage.java:80)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ApiCallTimeoutTrackingStage.execute(ApiCallTimeoutTrackingStage.java:60)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ApiCallTimeoutTrackingStage.execute(ApiCallTimeoutTrackingStage.java:42)
at software.amazon.awssdk.core.internal.http.pipeline.RequestPipelineBuilder$ComposingRequestPipelineStage.execute(RequestPipelineBuilder.java:206)
at software.amazon.awssdk.core.internal.http.pipeline.RequestPipelineBuilder$ComposingRequestPipelineStage.execute(RequestPipelineBuilder.java:206)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ExecutionFailureExceptionReportingStage.execute(ExecutionFailureExceptionReportingStage.java:37)
at software.amazon.awssdk.core.internal.http.pipeline.stages.ExecutionFailureExceptionReportingStage.execute(ExecutionFailureExceptionReportingStage.java:26)
at software.amazon.awssdk.core.internal.http.AmazonSyncHttpClient$RequestExecutionBuilderImpl.execute(AmazonSyncHttpClient.java:240)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler.invoke(BaseSyncClientHandler.java:96)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler.execute(BaseSyncClientHandler.java:120)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler.execute(BaseSyncClientHandler.java:61)
at software.amazon.awssdk.core.client.handler.SdkSyncClientHandler.execute(SdkSyncClientHandler.java:51)
at software.amazon.awssdk.awscore.client.handler.AwsSyncClientHandler.execute(AwsSyncClientHandler.java:62)
at software.amazon.awssdk.services.s3.DefaultS3Client.getObject(DefaultS3Client.java:1597)
at com.alshaya.phoenix.integration.s3.ObjectOperations.getObject(ObjectOperations.java:43)
at com.alshaya.phoenix.integration.s3.ObjectOperationsTestCase.tc4FileDownload(ObjectOperationsTestCase.java:100)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
Caused by: software.amazon.awssdk.core.exception.NonRetryableException
at software.amazon.awssdk.core.exception.NonRetryableException$BuilderImpl.build(NonRetryableException.java:91)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler$HttpResponseHandlerAdapter.transformResponse(BaseSyncClientHandler.java:161)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler$HttpResponseHandlerAdapter.handle(BaseSyncClientHandler.java:142)
at software.amazon.awssdk.core.internal.http.pipeline.stages.HandleResponseStage.handleSuccessResponse(HandleResponseStage.java:89)
... 56 more
Caused by: java.io.IOException: Failed to read response into file: C:\u04\out\test_file_0.bin
at software.amazon.awssdk.core.sync.ResponseTransformer.lambda$toFile$1(ResponseTransformer.java:113)
at software.amazon.awssdk.core.client.handler.BaseSyncClientHandler$HttpResponseHandlerAdapter.transformResponse(BaseSyncClientHandler.java:154)
... 58 more
Caused by: java.nio.file.FileAlreadyExistsException: C:\u04\out\test_file_0.bin
at sun.nio.fs.WindowsException.translateToIOException(Unknown Source)
at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at sun.nio.fs.WindowsException.rethrowAsIOException(Unknown Source)
at sun.nio.fs.WindowsFileSystemProvider.newByteChannel(Unknown Source)
at java.nio.file.spi.FileSystemProvider.newOutputStream(Unknown Source)
at java.nio.file.Files.newOutputStream(Unknown Source)
at java.nio.file.Files.copy(Unknown Source)
at software.amazon.awssdk.core.sync.ResponseTransformer.lambda$toFile$1(ResponseTransformer.java:106)
... 59 more

Answer 1

Since your file on the local drive already exists your code throws an exception. Try with a different file name or enabling overwrite if that is your intention.

Caused by: java.nio.file.FileAlreadyExistsException: C:\u04\out\test_file_0.bin