diff --git a/temporal-sdk/src/main/java/io/temporal/internal/statemachines/WorkflowStateMachines.java b/temporal-sdk/src/main/java/io/temporal/internal/statemachines/WorkflowStateMachines.java
index 65b490426..413a7c92d 100644
--- a/temporal-sdk/src/main/java/io/temporal/internal/statemachines/WorkflowStateMachines.java
+++ b/temporal-sdk/src/main/java/io/temporal/internal/statemachines/WorkflowStateMachines.java
@@ -260,7 +260,7 @@ public void setReplaying(boolean replaying) {
   }
 
   public void setMessages(List<Message> messages) {
-    this.messages = messages;
+    this.messages = new ArrayList<>(messages);
   }
 
   /**
diff --git a/temporal-sdk/src/test/java/io/temporal/internal/statemachines/UpdateProtocolStateMachineTest.java b/temporal-sdk/src/test/java/io/temporal/internal/statemachines/UpdateProtocolStateMachineTest.java
index 35f6fb47a..402c28471 100644
--- a/temporal-sdk/src/test/java/io/temporal/internal/statemachines/UpdateProtocolStateMachineTest.java
+++ b/temporal-sdk/src/test/java/io/temporal/internal/statemachines/UpdateProtocolStateMachineTest.java
@@ -43,10 +43,7 @@
 import io.temporal.internal.common.ProtobufTimeUtils;
 import io.temporal.internal.common.UpdateMessage;
 import java.time.Duration;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Optional;
+import java.util.*;
 import org.junit.AfterClass;
 import org.junit.Test;
 
@@ -98,6 +95,12 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
         builder
             .add(
                 (r) -> {
+                  if (message.getMessage().getId().startsWith("reject")) {
+                    message
+                        .getCallbacks()
+                        .reject(converter.exceptionToFailure(new RuntimeException()));
+                    return;
+                  }
                   message.getCallbacks().accept();
                 })
             .<HistoryEvent>add1(
@@ -122,8 +125,8 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
         2: EVENT_TYPE_WORKFLOW_TASK_SCHEDULED
         3: EVENT_TYPE_WORKFLOW_TASK_STARTED
         4: EVENT_TYPE_WORKFLOW_TASK_COMPLETED
-        5: EVENT_TYPE_TIMER_STARTED
-        6: EVENT_TYPE_WORKFLOW_EXECUTION_ACCEPTED
+        5: EVENT_TYPE_WORKFLOW_EXECUTION_ACCEPTED
+        6: EVENT_TYPE_TIMER_STARTED
         7: EVENT_TYPE_TIMER_FIRED
         8: EVENT_TYPE_WORKFLOW_TASK_SCHEDULED
         9: EVENT_TYPE_WORKFLOW_TASK_STARTED
@@ -194,6 +197,27 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
       List<Command> commands = h.handleWorkflowTaskTakeCommands(stateMachines);
       assertEquals(0, commands.size());
     }
+    {
+      TestEntityManagerListenerBase listener = new TestUpdateListener();
+      stateMachines = newStateMachines(listener);
+      stateMachines.setMessages(
+          Collections.unmodifiableList(
+              Arrays.asList(
+                  Message.newBuilder()
+                      .setProtocolInstanceId("reject_update_id")
+                      .setId("reject")
+                      .setEventId(9)
+                      .setBody(
+                          Any.pack(
+                              Request.newBuilder()
+                                  .setInput(Input.newBuilder().setName("updateName").build())
+                                  .build()))
+                      .build())));
+      List<Command> commands = h.handleWorkflowTaskTakeCommands(stateMachines, 1, 2);
+      assertEquals(CommandType.COMMAND_TYPE_PROTOCOL_MESSAGE, commands.get(0).getCommandType());
+      assertEquals(
+          CommandType.COMMAND_TYPE_COMPLETE_WORKFLOW_EXECUTION, commands.get(1).getCommandType());
+    }
   }
 
   @Test
@@ -205,17 +229,19 @@ public void buildWorkflow(AsyncWorkflowBuilder<Void> builder) {
         builder.add(
             (r) -> {
               stateMachines.setMessages(
-                  Arrays.asList(
-                      Message.newBuilder()
-                          .setProtocolInstanceId("protocol_id")
-                          .setId("id")
-                          .setEventId(2)
-                          .setBody(
-                              Any.pack(
-                                  Request.newBuilder()
-                                      .setInput(Input.newBuilder().setName("updateName").build())
-                                      .build()))
-                          .build()));
+                  Collections.unmodifiableList(
+                      Arrays.asList(
+                          Message.newBuilder()
+                              .setProtocolInstanceId("protocol_id")
+                              .setId("id")
+                              .setEventId(2)
+                              .setBody(
+                                  Any.pack(
+                                      Request.newBuilder()
+                                          .setInput(
+                                              Input.newBuilder().setName("updateName").build())
+                                          .build()))
+                              .build())));
             });
       }
 
@@ -387,15 +413,16 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
                           .setArgs(converter.toPayloads("arg").get()))
                   .build());
       stateMachines.setMessages(
-          Arrays.asList(
-              new Message[] {
-                Message.newBuilder()
-                    .setProtocolInstanceId("protocol_id")
-                    .setId("id")
-                    .setEventId(0)
-                    .setBody(messageBody)
-                    .build(),
-              }));
+          Collections.unmodifiableList(
+              Arrays.asList(
+                  new Message[] {
+                    Message.newBuilder()
+                        .setProtocolInstanceId("protocol_id")
+                        .setId("id")
+                        .setEventId(0)
+                        .setBody(messageBody)
+                        .build(),
+                  })));
       List<Command> commands = h.handleWorkflowTaskTakeCommands(stateMachines, 1);
       assertEquals(0, commands.size());
     }
@@ -494,17 +521,19 @@ public void buildWorkflow(AsyncWorkflowBuilder<Void> builder) {
         builder.add(
             (r) -> {
               stateMachines.setMessages(
-                  Arrays.asList(
-                      Message.newBuilder()
-                          .setProtocolInstanceId("message_updateID")
-                          .setId("message_updateID/request")
-                          .setEventId(6)
-                          .setBody(
-                              Any.pack(
-                                  Request.newBuilder()
-                                      .setInput(Input.newBuilder().setName("updateName").build())
-                                      .build()))
-                          .build()));
+                  Collections.unmodifiableList(
+                      Arrays.asList(
+                          Message.newBuilder()
+                              .setProtocolInstanceId("message_updateID")
+                              .setId("message_updateID/request")
+                              .setEventId(6)
+                              .setBody(
+                                  Any.pack(
+                                      Request.newBuilder()
+                                          .setInput(
+                                              Input.newBuilder().setName("updateName").build())
+                                          .build()))
+                              .build())));
             });
       }
 
@@ -528,8 +557,8 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
         2: EVENT_TYPE_WORKFLOW_TASK_SCHEDULED
         3: EVENT_TYPE_WORKFLOW_TASK_STARTED
         4: EVENT_TYPE_WORKFLOW_TASK_COMPLETED
-        5: EVENT_TYPE_WORKFLOW_TASK_SCHEDULED
-        6: EVENT_TYPE_WORKFLOW_EXECUTION_UPDATE_ADMITTED
+        5: EVENT_TYPE_WORKFLOW_EXECUTION_UPDATE_ADMITTED
+        6: EVENT_TYPE_WORKFLOW_TASK_SCHEDULED
         7: EVENT_TYPE_WORKFLOW_TASK_STARTED
     */
     TestHistoryBuilder h = new TestHistoryBuilder();
@@ -551,6 +580,12 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
       h.addWorkflowTaskScheduled();
       h.addWorkflowTaskStarted();
     }
+    {
+      // Full replay
+      TestEntityManagerListenerBase listener = new TestUpdateListener();
+      stateMachines = newStateMachines(listener);
+      List<Command> commands = h.handleWorkflowTaskTakeCommands(stateMachines, 1, 2);
+    }
     {
       // Full replay
       TestEntityManagerListenerBase listener = new TestUpdateListener();
@@ -840,17 +875,18 @@ protected void update(UpdateMessage message, AsyncWorkflowBuilder<Void> builder)
       TestEntityManagerListenerBase listener = new TestUpdateListener();
       stateMachines = newStateMachines(listener);
       stateMachines.setMessages(
-          Arrays.asList(
-              Message.newBuilder()
-                  .setProtocolInstanceId("message_update")
-                  .setId("message_update/request")
-                  .setEventId(7)
-                  .setBody(
-                      Any.pack(
-                          Request.newBuilder()
-                              .setInput(Input.newBuilder().setName("updateName").build())
-                              .build()))
-                  .build()));
+          Collections.unmodifiableList(
+              Arrays.asList(
+                  Message.newBuilder()
+                      .setProtocolInstanceId("message_update")
+                      .setId("message_update/request")
+                      .setEventId(7)
+                      .setBody(
+                          Any.pack(
+                              Request.newBuilder()
+                                  .setInput(Input.newBuilder().setName("updateName").build())
+                                  .build()))
+                      .build())));
       List<Command> commands = h.handleWorkflowTaskTakeCommands(stateMachines, 1, 2);
       assertEquals(6, commands.size());
       assertEquals(CommandType.COMMAND_TYPE_PROTOCOL_MESSAGE, commands.get(0).getCommandType());