diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
index ed36b27d2e1e3..bbd5f4428d604 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java
@@ -836,8 +836,10 @@ void setDisablePreUpgradableLayoutCheck(boolean val) {
    * @param sds A list of storage directories to mark as errored.
    */
   void reportErrorsOnDirectories(List<StorageDirectory> sds) {
-    for (StorageDirectory sd : sds) {
-      reportErrorsOnDirectory(sd);
+    synchronized(sds) {
+      for (StorageDirectory sd : sds) {
+        reportErrorsOnDirectory(sd);
+      }
     }
   }