From 4b7efb73f591a730e2f3dd0f7c2fa7827431081e Mon Sep 17 00:00:00 2001
From: Umeshkumar9414 <9414umeshkumar@gmail.com>
Date: Tue, 5 May 2026 13:34:19 +0530
Subject: [PATCH] HBASE-30142 Resolve NPE while running recoverUnknown command
 because null RegionLocation

---
 .../org/apache/hadoop/hbase/master/ServerManager.java    | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
index 09184975a33c..8f7cf4488349 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ServerManager.java
@@ -980,11 +980,14 @@ public synchronized boolean isServerDead(ServerName serverName) {
   /**
    * Check if a server is unknown. A server can be online, or known to be dead, or unknown to this
    * manager (i.e, not online, not known to be dead either; it is simply not tracked by the master
-   * any more, for example, a very old previous instance).
+   * any more, for example, a very old previous instance). A null serverName should not be
+   * considered unknown. We set regionLocation null before finding the assign candidate (in-between
+   * region transition) or while marking it OFFLINE/FAILED_OPEN For more info regarding null-check
+   * in this refer HBASE-30142
    */
   public boolean isServerUnknown(ServerName serverName) {
-    return serverName == null
-      || (!onlineServers.containsKey(serverName) && !deadservers.isDeadServer(serverName));
+    return serverName != null
+      && (!onlineServers.containsKey(serverName) && !deadservers.isDeadServer(serverName));
   }
 
   public void shutdownCluster() {