diff --git a/nifi-mock/src/main/java/org/apache/nifi/util/StandardProcessorTestRunner.java b/nifi-mock/src/main/java/org/apache/nifi/util/StandardProcessorTestRunner.java
index 7de3bbe6d7..27d642e73c 100644
--- a/nifi-mock/src/main/java/org/apache/nifi/util/StandardProcessorTestRunner.java
+++ b/nifi-mock/src/main/java/org/apache/nifi/util/StandardProcessorTestRunner.java
@@ -187,7 +187,7 @@ public class StandardProcessorTestRunner implements TestRunner {
 
     @Override
     public void run(final int iterations, final boolean stopOnFinish, final boolean initialize, final long runWait) {
-        if (iterations < 1) {
+        if (iterations < 0) {
             throw new IllegalArgumentException();
         }
 
diff --git a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ExecuteProcess.java b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ExecuteProcess.java
index ffc8032f9d..244d5aaa23 100644
--- a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ExecuteProcess.java
+++ b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/ExecuteProcess.java
@@ -207,7 +207,7 @@ public class ExecuteProcess extends AbstractProcessor {
         try {
             executor.shutdown();
         } finally {
-            if (this.externalProcess.isAlive()) {
+            if ((this.externalProcess != null) && (this.externalProcess.isAlive())) {
                 this.getLogger().info("Process hasn't terminated, forcing the interrupt");
                 this.externalProcess.destroyForcibly();
             }
diff --git a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestExecuteProcess.java b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestExecuteProcess.java
index a5a08f0898..5972caf8fc 100644
--- a/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestExecuteProcess.java
+++ b/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestExecuteProcess.java
@@ -313,4 +313,15 @@ public class TestExecuteProcess {
                     .anyMatch(m -> m.getMsg().contains("Failed to create process due to")));
     }
 
+    /**
+     * On configuration of this processor to run only on primary cluster node, other nodes call
+     * {@link org.apache.nifi.annotation.lifecycle.OnUnscheduled} method after an invocation (Start/Stop or RunOnce),
+     * causing an NPE.  NPE guard added; test for this situation.
+     */
+    @Test
+    public void testProcessorNotScheduled() {
+        final TestRunner runner = TestRunners.newTestRunner(ExecuteProcess.class);
+        runner.setProperty(ExecuteProcess.COMMAND, "ls");
+        runner.run(0);
+    }
 }