diff --git a/CHANGES.txt b/CHANGES.txt
index 062811b158..9107756a87 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -3,6 +3,7 @@
  * Fix BulkLoader ignoring cipher suites options (CASSANDRA-18582)
  * Migrate Python optparse to argparse (CASSANDRA-17914)
 Merged from 3.11:
+ * Fix NPE when using udfContext in UDF after a restart of a node (CASSANDRA-18739)
  * Moved jflex from runtime to build dependencies (CASSANDRA-18664)
 Merged from 3.0:
  * Backport of CASSANDRA-16905 Further restrict schema column drop/recreate conversions (CASSANDRA-18760)
diff --git a/src/java/org/apache/cassandra/cql3/functions/UDFContextImpl.java b/src/java/org/apache/cassandra/cql3/functions/UDFContextImpl.java
index d4bdf203a2..134dea570a 100644
--- a/src/java/org/apache/cassandra/cql3/functions/UDFContextImpl.java
+++ b/src/java/org/apache/cassandra/cql3/functions/UDFContextImpl.java
@@ -22,12 +22,16 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.function.Supplier;
+
+import com.google.common.base.Suppliers;
 
 import org.apache.cassandra.cql3.ColumnIdentifier;
 import org.apache.cassandra.db.marshal.AbstractType;
 import org.apache.cassandra.schema.CQLTypeParser;
 import org.apache.cassandra.schema.KeyspaceMetadata;
 import org.apache.cassandra.cql3.functions.types.*;
+import org.apache.cassandra.schema.Schema;
 import org.apache.cassandra.utils.ByteBufferUtil;
 
 /**
@@ -35,19 +39,25 @@ import org.apache.cassandra.utils.ByteBufferUtil;
  */
 public final class UDFContextImpl implements UDFContext
 {
-    private final KeyspaceMetadata keyspaceMetadata;
     private final Map<String, TypeCodec<Object>> byName = new HashMap<>();
     private final TypeCodec<Object>[] argCodecs;
     private final TypeCodec<Object> returnCodec;
+    private final String keyspace;
 
-    UDFContextImpl(List<ColumnIdentifier> argNames, TypeCodec<Object>[] argCodecs, TypeCodec<Object> returnCodec,
-                   KeyspaceMetadata keyspaceMetadata)
+    /*
+        metadata can not be retrieved within the constructor as the keyspace itself may be being
+        constructed and an NPE will result.
+     */
+    private final Supplier<KeyspaceMetadata> metadata;
+
+    UDFContextImpl(List<ColumnIdentifier> argNames, TypeCodec<Object>[] argCodecs, TypeCodec<Object> returnCodec, String keyspace)
     {
         for (int i = 0; i < argNames.size(); i++)
             byName.put(argNames.get(i).toString(), argCodecs[i]);
         this.argCodecs = argCodecs;
         this.returnCodec = returnCodec;
-        this.keyspaceMetadata = keyspaceMetadata;
+        this.keyspace = keyspace;
+        this.metadata = Suppliers.memoize(() -> Schema.instance.getKeyspaceMetadata(keyspace));
     }
 
     public UDTValue newArgUDTValue(String argName)
@@ -67,9 +77,9 @@ public final class UDFContextImpl implements UDFContext
 
     public UDTValue newUDTValue(String udtName)
     {
-        Optional<org.apache.cassandra.db.marshal.UserType> udtType = keyspaceMetadata.types.get(ByteBufferUtil.bytes(udtName));
+        Optional<org.apache.cassandra.db.marshal.UserType> udtType = metadata.get().types.get(ByteBufferUtil.bytes(udtName));
         DataType dataType = UDHelper.driverType(udtType.orElseThrow(
-                () -> new IllegalArgumentException("No UDT named " + udtName + " in keyspace " + keyspaceMetadata.name)
+                () -> new IllegalArgumentException("No UDT named " + udtName + " in keyspace " + keyspace)
             ));
         return newUDTValue(dataType);
     }
@@ -91,7 +101,7 @@ public final class UDFContextImpl implements UDFContext
 
     public TupleValue newTupleValue(String cqlDefinition)
     {
-        AbstractType<?> abstractType = CQLTypeParser.parse(keyspaceMetadata.name, cqlDefinition, keyspaceMetadata.types);
+        AbstractType<?> abstractType = CQLTypeParser.parse(keyspace, cqlDefinition, metadata.get().types);
         DataType dataType = UDHelper.driverType(abstractType);
         return newTupleValue(dataType);
     }
diff --git a/src/java/org/apache/cassandra/cql3/functions/UDFunction.java b/src/java/org/apache/cassandra/cql3/functions/UDFunction.java
index 3863f89828..04bd8265f5 100644
--- a/src/java/org/apache/cassandra/cql3/functions/UDFunction.java
+++ b/src/java/org/apache/cassandra/cql3/functions/UDFunction.java
@@ -232,9 +232,7 @@ public abstract class UDFunction extends AbstractFunction implements ScalarFunct
         this.argCodecs = UDHelper.codecsFor(argDataTypes);
         this.returnCodec = UDHelper.codecFor(returnDataType);
         this.calledOnNullInput = calledOnNullInput;
-        KeyspaceMetadata keyspaceMetadata = Schema.instance.getKeyspaceMetadata(name.keyspace);
-        this.udfContext = new UDFContextImpl(argNames, argCodecs, returnCodec,
-                                             keyspaceMetadata);
+        this.udfContext = new UDFContextImpl(argNames, argCodecs, returnCodec, name.keyspace);
     }
 
     public static UDFunction tryCreate(FunctionName name,
diff --git a/test/distributed/org/apache/cassandra/distributed/test/UDFTest.java b/test/distributed/org/apache/cassandra/distributed/test/UDFTest.java
new file mode 100644
index 0000000000..37ec95d5f5
--- /dev/null
+++ b/test/distributed/org/apache/cassandra/distributed/test/UDFTest.java
@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.cassandra.distributed.test;
+
+import org.junit.Test;
+
+import org.apache.cassandra.distributed.Cluster;
+
+import static java.lang.Boolean.TRUE;
+import static org.apache.cassandra.distributed.api.ConsistencyLevel.ALL;
+import static org.apache.cassandra.distributed.shared.AssertUtils.assertRows;
+import static org.apache.cassandra.distributed.shared.AssertUtils.row;
+
+public class UDFTest extends TestBaseImpl
+{
+    @Test
+    public void testUDFContextKeyspaceNotNull() throws Throwable
+    {
+        /*
+        To test the keyspace is not null in the context we call UDFContext.newUDTValue() because it
+        relies on the keyspace not being null.
+         */
+        String[] createStmts = {
+        "CREATE TABLE " + KEYSPACE + ".current (city text, PRIMARY KEY (city))",
+        "CREATE TYPE IF NOT EXISTS " + KEYSPACE + ".aggst (lt int, ge int)",
+        "CREATE FUNCTION " + KEYSPACE + ".udf_not_null ()\n" +
+        "CALLED ON NULL INPUT\n" +
+        "RETURNS boolean LANGUAGE java AS $$\n" +
+        "udfContext.newUDTValue(\"aggst\");\n" +
+        "return Boolean.TRUE;\n" +
+        "$$;",
+        };
+
+        try (Cluster cluster = init(Cluster.create(1, config -> config.set("enable_user_defined_functions", "true"))))
+        {
+            for (String stmt : createStmts)
+                cluster.schemaChange(stmt);
+
+            cluster.coordinator(1).execute("INSERT INTO " + KEYSPACE + ".current (city) VALUES ('Helsinki')", ALL);
+
+            assertRows(cluster.coordinator(1).execute("SELECT " + KEYSPACE + ".udf_not_null() AS m FROM " + KEYSPACE + ".current", ALL), row(TRUE));
+
+            cluster.get(1).shutdown().get();
+            cluster.get(1).startup();
+
+            assertRows(cluster.coordinator(1).execute("SELECT " + KEYSPACE + ".udf_not_null() AS m FROM " + KEYSPACE + ".current", ALL), row(TRUE));
+        }
+    }
+}