diff --git a/hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/nfs/NfsExports.java b/hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/nfs/NfsExports.java
index 9628686538..b617ae5088 100644
--- a/hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/nfs/NfsExports.java
+++ b/hadoop-common-project/hadoop-nfs/src/main/java/org/apache/hadoop/nfs/NfsExports.java
@@ -53,7 +53,12 @@ public static synchronized NfsExports getInstance(Configuration conf) {
       long expirationPeriodNano = conf.getLong(
           Nfs3Constant.NFS_EXPORTS_CACHE_EXPIRYTIME_MILLIS_KEY,
           Nfs3Constant.NFS_EXPORTS_CACHE_EXPIRYTIME_MILLIS_DEFAULT) * 1000 * 1000;
-      exports = new NfsExports(cacheSize, expirationPeriodNano, matchHosts);
+      try {
+        exports = new NfsExports(cacheSize, expirationPeriodNano, matchHosts);
+      } catch (IllegalArgumentException e) {
+        LOG.error("Invalid NFS Exports provided: ", e);
+        return exports;
+      }
     }
     return exports;
   }
diff --git a/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/mount/RpcProgramMountd.java b/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/mount/RpcProgramMountd.java
index 9fbab240f6..2814cb007e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/mount/RpcProgramMountd.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/mount/RpcProgramMountd.java
@@ -104,6 +104,10 @@ public XDR nullOp(XDR out, int xid, InetAddress client) {
 
   @Override
   public XDR mnt(XDR xdr, XDR out, int xid, InetAddress client) {
+    if (hostsMatcher == null) {
+      return MountResponse.writeMNTResponse(Nfs3Status.NFS3ERR_ACCES, out, xid,
+          null);
+    }
     AccessPrivilege accessPrivilege = hostsMatcher.getAccessPrivilege(client);
     if (accessPrivilege == AccessPrivilege.NONE) {
       return MountResponse.writeMNTResponse(Nfs3Status.NFS3ERR_ACCES, out, xid,
@@ -208,16 +212,23 @@ public void handleInternal(ChannelHandlerContext ctx, RpcInfo info) {
     } else if (mntproc == MNTPROC.UMNTALL) {
       umntall(out, xid, client);
     } else if (mntproc == MNTPROC.EXPORT) {
-      // Currently only support one NFS export 
+      // Currently only support one NFS export
       List<NfsExports> hostsMatchers = new ArrayList<NfsExports>();
-      hostsMatchers.add(hostsMatcher);
-      out = MountResponse.writeExportList(out, xid, exports, hostsMatchers);
+      if (hostsMatcher != null) {
+        hostsMatchers.add(hostsMatcher);
+        out = MountResponse.writeExportList(out, xid, exports, hostsMatchers);
+      } else {
+        // This means there are no valid exports provided.
+        RpcAcceptedReply.getInstance(xid,
+          RpcAcceptedReply.AcceptState.PROC_UNAVAIL, new VerifierNone()).write(
+          out);
+      }
     } else {
       // Invalid procedure
       RpcAcceptedReply.getInstance(xid,
           RpcAcceptedReply.AcceptState.PROC_UNAVAIL, new VerifierNone()).write(
           out);
-    }  
+    }
     ChannelBuffer buf = ChannelBuffers.wrappedBuffer(out.asReadOnlyWrap().buffer());
     RpcResponse rsp = new RpcResponse(buf, info.remoteAddress());
     RpcUtil.sendRpcResponse(ctx, rsp);
diff --git a/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/RpcProgramNfs3.java b/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/RpcProgramNfs3.java
index f254f50709..1650b14724 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/RpcProgramNfs3.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/RpcProgramNfs3.java
@@ -2123,8 +2123,11 @@ private boolean checkAccessPrivilege(SocketAddress remoteAddress,
     if (!doPortMonitoring(remoteAddress)) {
       return false;
     }
-    
+
     // Check export table
+    if (exports == null) {
+        return false;
+    }
     InetAddress client = ((InetSocketAddress) remoteAddress).getAddress();
     AccessPrivilege access = exports.getAccessPrivilege(client);
     if (access == AccessPrivilege.NONE) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 63168e0ca2..bbeebd1984 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -361,6 +361,9 @@ Release 2.6.0 - UNRELEASED
     continuously leading to huge size of dncp_block_verification.log.curr
     (vinayakumarb via cmccabe)
 
+    HDFS-6455. NFS: Exception should be added in NFS log for invalid separator in
+    nfs.exports.allowed.hosts. (Abhiraj Butala via brandonli)
+
 Release 2.5.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES