title: com.amazonaws.services.s3.model.AmazonS3Exception: User key must be specified
body: <pre><code>com.amazonaws.services.s3.model.AmazonS3Exception: User key must be specified. (Service: Amazon S3; Status Code: 400;
         at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:1160)
         at com.amazonaws.http.AmazonHttpClient.executeOneRequest(AmazonHttpClient.java:748)
         at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:467)
         at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:302)
         at com.amazonaws.services.s3.AmazonS3Client.invoke(AmazonS3Client.java:3769)
         at com.amazonaws.services.s3.AmazonS3Client.deleteObjects(AmazonS3Client.java:1841)
  </code></pre>
  
  <p>The code looks like below: </p>
  
  <pre><code>client.deleteObjects(new DeleteObjectsRequest(bucketName).withKeys(keys.toArray(new String[urls.length]))
  </code></pre>
  
  <p>access/secret keys are set up properly.</p>
  
  <p>What is the <strong>user key</strong>?</p>