diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/DataNodeUGIProvider.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/DataNodeUGIProvider.java
index 366f47f296..d7e5f9f155 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/DataNodeUGIProvider.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/DataNodeUGIProvider.java
@@ -72,9 +72,12 @@ UserGroupInformation ugi() throws IOException {
     UserGroupInformation ugi;
 
     try {
-      if (UserGroupInformation.isSecurityEnabled()) {
-        final Token<DelegationTokenIdentifier> token = params.delegationToken();
+      final Token<DelegationTokenIdentifier> token = params.delegationToken();
 
+      // Create nonTokenUGI when token is null regardless of security.
+      // This makes it possible to access the data stored in secure DataNode
+      // through insecure Namenode.
+      if (UserGroupInformation.isSecurityEnabled() && token != null) {
         ugi = ugiCache.get(buildTokenCacheKey(token),
             new Callable<UserGroupInformation>() {
               @Override
@@ -134,7 +137,8 @@ private String buildNonTokenCacheKey(String doAsUserFromQuery,
     return key;
   }
 
-  private UserGroupInformation nonTokenUGI(String usernameFromQuery,
+  @VisibleForTesting
+  UserGroupInformation nonTokenUGI(String usernameFromQuery,
       String doAsUserFromQuery, String remoteUser) throws IOException {
 
     UserGroupInformation ugi = UserGroupInformation
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
index 2b3a39358d..c4588fc657 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/ParameterParser.java
@@ -123,6 +123,9 @@ boolean noredirect() {
 
   Token<DelegationTokenIdentifier> delegationToken() throws IOException {
     String delegation = param(DelegationParam.NAME);
+    if (delegation == null) {
+      return null;
+    }
     final Token<DelegationTokenIdentifier> token = new
       Token<DelegationTokenIdentifier>();
     token.decodeFromUrlString(delegation);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/WebHdfsHandler.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/WebHdfsHandler.java
index ff68a7ee7e..834d9d5e1d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/WebHdfsHandler.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/WebHdfsHandler.java
@@ -335,8 +335,8 @@ private static void writeContinueHeader(ChannelHandlerContext ctx) {
   }
 
   private void injectToken() throws IOException {
-    if (UserGroupInformation.isSecurityEnabled()) {
-      Token<DelegationTokenIdentifier> token = params.delegationToken();
+    Token<DelegationTokenIdentifier> token = params.delegationToken();
+    if (UserGroupInformation.isSecurityEnabled() && token != null) {
       token.setKind(HDFS_DELEGATION_KIND);
       ugi.addToken(token);
     }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestDataNodeUGIProvider.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestDataNodeUGIProvider.java
index de88c51ed2..102418517f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestDataNodeUGIProvider.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestDataNodeUGIProvider.java
@@ -20,6 +20,8 @@
 
 import static org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod.KERBEROS;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
 import io.netty.handler.codec.http.QueryStringDecoder;
 
 import java.io.IOException;
@@ -31,6 +33,7 @@
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSecretManager;
+import org.apache.hadoop.hdfs.server.common.JspHelper;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.hdfs.web.WebHdfsConstants;
 import org.apache.hadoop.hdfs.web.WebHdfsFileSystem;
@@ -186,6 +189,35 @@ public void testUGICacheInSecure() throws Exception {
         ugi11, url22);
   }
 
+  @Test
+  public void testUGINullTokenSecure() throws IOException {
+    SecurityUtil.setAuthenticationMethod(KERBEROS, conf);
+    UserGroupInformation.setConfiguration(conf);
+
+    String uri1 = WebHdfsFileSystem.PATH_PREFIX
+            + PATH
+            + "?op=OPEN"
+            + Param.toSortedString("&", new OffsetParam((long) OFFSET),
+            new LengthParam((long) LENGTH), new UserParam("root"));
+
+    ParameterParser params = new ParameterParser(
+            new QueryStringDecoder(URI.create(uri1)), conf);
+
+    DataNodeUGIProvider ugiProvider = new DataNodeUGIProvider(params);
+
+    String usernameFromQuery = params.userName();
+    String doAsUserFromQuery = params.doAsUser();
+    String remoteUser = usernameFromQuery == null ? JspHelper
+            .getDefaultWebUserName(params.conf())
+            : usernameFromQuery;
+
+    DataNodeUGIProvider spiedUGIProvider = spy(ugiProvider);
+    spiedUGIProvider.ugi();
+
+    verify(spiedUGIProvider).nonTokenUGI(usernameFromQuery, doAsUserFromQuery,
+            remoteUser);
+  }
+
   /**
    * Wait for expiration of entries from the UGI cache.  We need to be careful
    * not to touch the entries in the cache while we're waiting for expiration.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
index 235d051400..40409985c3 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/web/webhdfs/TestParameterParser.java
@@ -55,6 +55,15 @@ public void testDeserializeHAToken() throws IOException {
     Assert.assertTrue(HAUtilClient.isTokenForLogicalUri(tok2));
   }
 
+  @Test
+  public void testNullToken() throws IOException {
+    Configuration conf = new Configuration();
+    QueryStringDecoder decoder = new QueryStringDecoder(
+            WebHdfsHandler.WEBHDFS_PREFIX + "/test");
+    ParameterParser testParser = new ParameterParser(decoder, conf);
+    Assert.assertNull(testParser.delegationToken());
+  }
+
   @Test
   public void testDecodePath() {
     final String ESCAPED_PATH = "/test%25+1%26%3Dtest?op=OPEN&foo=bar";