diff --git a/plugin/src/main/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecution.java b/plugin/src/main/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecution.java
index 683eecdf9..181471b5a 100644
--- a/plugin/src/main/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecution.java
+++ b/plugin/src/main/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecution.java
@@ -1276,6 +1276,8 @@ public List<Action> loadActions(FlowNode node) throws IOException {
     public void saveActions(FlowNode node, List<Action> actions) throws IOException {
         if (storage == null) {
             throw new IOException("storage not yet loaded");
+        } else if (isComplete()) {
+            throw new IOException("Cannot save actions for " + node + " for completed execution " + this + ": " + actions);
         }
         storage.saveActions(node, actions);
     }
diff --git a/plugin/src/test/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecutionTest.java b/plugin/src/test/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecutionTest.java
index 325ec7d83..f6687b930 100644
--- a/plugin/src/test/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecutionTest.java
+++ b/plugin/src/test/java/org/jenkinsci/plugins/workflow/cps/CpsFlowExecutionTest.java
@@ -33,6 +33,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
@@ -49,6 +50,7 @@
 import hudson.model.Result;
 import hudson.model.TaskListener;
 import java.io.File;
+import java.io.IOException;
 import java.io.Serializable;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
@@ -914,4 +916,15 @@ public boolean takesImplicitBlockArgument() {
         });
     }
 
+    @Test public void flowNodesCantBeSavedAfterExecutionCompletes() throws Throwable {
+        sessions.then(r -> {
+            WorkflowJob p = r.createProject(WorkflowJob.class, "p");
+            p.setDefinition(new CpsFlowDefinition("echo 'Hello, world!'", true));
+            WorkflowRun b = r.buildAndAssertSuccess(p);
+            FlowNode echoStep = b.getExecution().getNode("3");
+            IOException e = assertThrows(IOException.class, echoStep::save);
+            assertThat(e.getMessage(), containsString("Cannot save actions for " + echoStep + " for completed execution " + b.getExecution()));
+        });
+    }
+
 }