HDFS-7305. NPE seen in wbhdfs FS while running SLive. Contributed by Jing Zhao.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -973,6 +973,7 @@ Release 2.6.0 - UNRELEASED
     HDFS-7300. The getMaxNodesPerRack() method in BlockPlacementPolicyDefault
     is flawed (kihwal)
 
+    HDFS-7305. NPE seen in wbhdfs FS while running SLive. (jing9)
 
   BREAKDOWN OF HDFS-6584 ARCHIVAL STORAGE
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -355,7 +355,7 @@ public class WebHdfsFileSystem extends FileSystem
       // extract UGI-related exceptions and unwrap InvalidToken
       // the NN mangles these exceptions but the DN does not and may need
       // to re-fetch a token if either report the token is expired
-      if (re.getMessage().startsWith(
+      if (re.getMessage() != null && re.getMessage().startsWith(
           SecurityUtil.FAILED_TO_GET_UGI_MSG_HEADER)) {
         String[] parts = re.getMessage().split(":\\s+", 3);
         re = new RemoteException(parts[1], parts[2]);