From 10311c30b02d984a11f2cedfd06eb2a766ad1576 Mon Sep 17 00:00:00 2001
From: Wei-Chiu Chuang <weichiu@apache.org>
Date: Mon, 17 Jun 2019 19:55:56 -0700
Subject: [PATCH] HADOOP-14807. should prevent the possibility of NPE about
 ReconfigurableBase.java. Contributed by hu xiaodong.

---
 .../main/java/org/apache/hadoop/conf/ReconfigurableBase.java   | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurableBase.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurableBase.java
index 23e1fda905..8cacbdcdac 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurableBase.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/ReconfigurableBase.java
@@ -146,7 +146,8 @@ public abstract class ReconfigurableBase
             oldConf.unset(change.prop);
           }
         } catch (ReconfigurationException e) {
-          errorMessage = e.getCause().getMessage();
+          Throwable cause = e.getCause();
+          errorMessage = cause == null ? e.getMessage() : cause.getMessage();
         }
         results.put(change, Optional.ofNullable(errorMessage));
       }