diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java
index 5baf30846e08..cce8cb85973d 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java
@@ -786,6 +786,10 @@ private TransitRegionStateProcedure createAssignProcedure(RegionInfo regionInfo,
     RegionStateNode regionNode = regionStates.getOrCreateRegionStateNode(regionInfo);
     regionNode.lock();
     try {
+      if (regionNode.isSplit()) {
+        throw new DoNotRetryRegionException(regionNode.getRegionInfo().getEncodedName()
+          + " is a split parent and cannot be assigned");
+      }
       if (override) {
         if (!force) {
           preTransitCheck(regionNode, STATES_EXPECTED_ON_ASSIGN);
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStateStore.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStateStore.java
index 6dac4c37c1b3..8b2003bfb207 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStateStore.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionStateStore.java
@@ -376,6 +376,8 @@ public void splitRegion(RegionInfo parent, RegionInfo splitA, RegionInfo splitB,
     Put putParent = MetaTableAccessor.makePutFromRegionInfo(
       RegionInfoBuilder.newBuilder(parent).setOffline(true).setSplit(true).build(), time);
     MetaTableAccessor.addDaughtersToPut(putParent, splitA, splitB);
+    MetaTableAccessor.addRegionStateToPut(putParent, RegionInfo.DEFAULT_REPLICA_ID,
+      RegionState.State.SPLIT);
 
     // Puts for daughters
     Put putA = MetaTableAccessor.makePutFromRegionInfo(splitA, time);
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestAssignmentManager.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestAssignmentManager.java
index 01d051779058..e53ff50ea0b8 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestAssignmentManager.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestAssignmentManager.java
@@ -20,11 +20,13 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Collections;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
+import org.apache.hadoop.hbase.DoNotRetryIOException;
 import org.apache.hadoop.hbase.HBaseTestingUtil;
 import org.apache.hadoop.hbase.MetaTableAccessor;
 import org.apache.hadoop.hbase.TableName;
@@ -217,6 +219,31 @@ public void testUnassignAnUnassignedRegion() throws Exception {
     assertEquals(unassignFailedCount, unassignProcMetrics.getFailedCounter().getCount());
   }
 
+  @Test
+  public void testAssignThrowsWithASplitParent() throws Exception {
+    RegionInfo splitParent = RegionInfoBuilder.newBuilder(TableName.valueOf("test-split-split"))
+      .setSplit(true).setOffline(true).build();
+    RegionStateNode rsn = am.getRegionStates().getOrCreateRegionStateNode(splitParent);
+    rsn.setState(State.SPLIT);
+
+    assertThrows(DoNotRetryIOException.class, () -> am.assign(splitParent));
+    assertNull(am.createOneAssignProcedure(splitParent, true, false));
+  }
+
+  // Simulate the pre-fix failover scenario: regionInfo.isSplit()=true but state=OFFLINE because
+  // the old code path did not write SPLIT to info:state, causing loadMeta to fall back to OFFLINE.
+  // See HBASE-30353.
+  @Test
+  public void testAssignThrowsWithASplitParentInOfflineState() throws Exception {
+    RegionInfo splitParent = RegionInfoBuilder.newBuilder(TableName.valueOf("test-split-offline"))
+      .setSplit(true).setOffline(true).build();
+    RegionStateNode rsn = am.getRegionStates().getOrCreateRegionStateNode(splitParent);
+    rsn.setState(State.OFFLINE);
+
+    assertThrows(DoNotRetryIOException.class, () -> am.assign(splitParent));
+    assertNull(am.createOneAssignProcedure(splitParent, true, false));
+  }
+
   /**
    * It is possible that when AM send assign meta request to a RS successfully, but RS can not send
    * back any response, which cause master startup hangs forever
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionStateStore.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionStateStore.java
index b85b7c606063..d0fdb09503b8 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionStateStore.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionStateStore.java
@@ -221,6 +221,37 @@ public void testEmptyMetaDaughterLocationDuringSplit() throws IOException {
     }
   }
 
+  @Test
+  public void testSplitRegionWritesSplitStateForParentInMeta() throws IOException {
+    long regionId = EnvironmentEdgeManager.currentTime();
+    ServerName serverName =
+      ServerName.valueOf("foo", 60010, ThreadLocalRandom.current().nextLong());
+    TableName tableName = name.getTableName();
+    RegionInfo parent = RegionInfoBuilder.newBuilder(tableName)
+      .setStartKey(HConstants.EMPTY_START_ROW).setEndKey(HConstants.EMPTY_END_ROW).setSplit(false)
+      .setRegionId(regionId).setReplicaId(0).build();
+    RegionInfo splitA = RegionInfoBuilder.newBuilder(tableName)
+      .setStartKey(HConstants.EMPTY_START_ROW).setEndKey(Bytes.toBytes("a")).setSplit(false)
+      .setRegionId(regionId + 1).setReplicaId(0).build();
+    RegionInfo splitB = RegionInfoBuilder.newBuilder(tableName).setStartKey(Bytes.toBytes("a"))
+      .setEndKey(HConstants.EMPTY_END_ROW).setSplit(false).setRegionId(regionId + 1).setReplicaId(0)
+      .build();
+    MetaTableAccessor.addRegionsToMeta(UTIL.getConnection(), Lists.newArrayList(parent), 1);
+    final RegionStateStore regionStateStore =
+      UTIL.getHBaseCluster().getMaster().getAssignmentManager().getRegionStateStore();
+    regionStateStore.splitRegion(parent, splitA, splitB, serverName,
+      TableDescriptorBuilder.newBuilder(tableName).build());
+
+    try (Table meta = MetaTableAccessor.getMetaHTable(UTIL.getConnection())) {
+      Result result = meta.get(new Get(parent.getRegionName()));
+      Cell stateCell = result.getColumnLatestCell(HConstants.CATALOG_FAMILY,
+        CatalogFamilyFormat.getRegionStateColumn(RegionInfo.DEFAULT_REPLICA_ID));
+      assertNotNull(stateCell);
+      assertEquals(RegionState.State.SPLIT.name(), Bytes.toString(stateCell.getValueArray(),
+        stateCell.getValueOffset(), stateCell.getValueLength()));
+    }
+  }
+
   @Test
   public void testMetaLocationForRegionReplicasIsAddedAtRegionMerge() throws IOException {
     long regionId = EnvironmentEdgeManager.currentTime();