diff --git a/Test/DurableTask.Core.Tests/TestTaskEntityDispatcher.cs b/Test/DurableTask.Core.Tests/TestTaskEntityDispatcher.cs
new file mode 100644
index 000000000..3e5032156
--- /dev/null
+++ b/Test/DurableTask.Core.Tests/TestTaskEntityDispatcher.cs
@@ -0,0 +1,88 @@
+using DurableTask.Core.Entities;
+using DurableTask.Core.Entities.OperationFormat;
+using DurableTask.Core.History;
+using DurableTask.Core.Logging;
+using DurableTask.Core.Middleware;
+using DurableTask.Emulator;
+using DurableTask.Test.Orchestrations;
+using Microsoft.Extensions.Logging;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Collections.Generic;
+using static DurableTask.Core.TaskEntityDispatcher;
+
+namespace DurableTask.Core.Tests
+{
+    [TestClass]
+    public class TestTaskEntityDispatcher
+    {
+        /// <summary>
+        /// Utiliy function to create a TaskEntityDispatcher instance. To be expanded upon as per testing needs.
+        /// </summary>
+        /// <returns></returns>
+        private TaskEntityDispatcher GetTaskEntityDispatcher()
+        {
+            // TODO: these should probably be injectable parameters to this method,
+            // initialized with sensible defaults if not provided
+            var service = new LocalOrchestrationService();
+            ILoggerFactory loggerFactory = null;
+            var entityManager = new NameVersionObjectManager<TaskEntity>();
+            var entityMiddleware = new DispatchMiddlewarePipeline();
+            var logger = new LogHelper(loggerFactory?.CreateLogger("DurableTask.Core"));
+
+            TaskEntityDispatcher dispatcher = new TaskEntityDispatcher(
+                service, entityManager, entityMiddleware, logger, ErrorPropagationMode.UseFailureDetails);
+            return dispatcher;
+        }
+
+        /// <summary>
+        /// See: https://github.com/Azure/durabletask/pull/1080
+        /// This test is motivated by a regression where Entities
+        /// that scheduled sub-orchestrators would incorrectly set
+        /// the FireAndForget tag on the ExecutionStartedEvent, causing
+        /// them to then receive a SubOrchestrationCompleted event, which
+        /// they did not know how to handle. Eventually, this led to them deleting
+        /// their own state. This test checks against that case.
+        /// </summary>
+        [TestMethod]
+        public void TestEntityDoesNotSetFireAndForgetTags()
+        {
+            TaskEntityDispatcher dispatcher = GetTaskEntityDispatcher();
+
+            // Prepare effects
+            var effects = new WorkItemEffects();
+            effects.taskIdCounter = 0;
+            effects.InstanceMessages = new List<TaskMessage>();
+
+            // Prepare runtime state
+            var mockEntityStartEvent = new ExecutionStartedEvent(-1, null)
+            {
+                OrchestrationInstance = new OrchestrationInstance(),
+                Name = "testentity",
+                Version = "1.0",
+            };
+            var runtimeState = new OrchestrationRuntimeState();
+            runtimeState.AddEvent(mockEntityStartEvent);
+
+            // Prepare action.
+            // This mocks starting a new orchestration from an entity.
+            var action = new StartNewOrchestrationOperationAction()
+            {
+                InstanceId = "testsample",
+                Name = "test",
+                Version = "1.0",
+                Input = null,
+            };
+
+            // Invoke the dispatcher and obtain resulting event
+            dispatcher.ProcessSendStartMessage(effects, runtimeState, action);
+            HistoryEvent resultEvent = effects.InstanceMessages[0].Event;
+
+            Assert.IsInstanceOfType(resultEvent, typeof(ExecutionStartedEvent));
+            var executionStartedEvent = (ExecutionStartedEvent)resultEvent;
+
+            // The resulting event should contain a fire and forget tag
+            bool hasFireAndForgetTag = executionStartedEvent.Tags.ContainsKey(OrchestrationTags.FireAndForget);
+            Assert.IsTrue(hasFireAndForgetTag);
+        }
+    }
+}
diff --git a/src/DurableTask.Core/TaskEntityDispatcher.cs b/src/DurableTask.Core/TaskEntityDispatcher.cs
index 8e6dd7d8d..a7ecb5267 100644
--- a/src/DurableTask.Core/TaskEntityDispatcher.cs
+++ b/src/DurableTask.Core/TaskEntityDispatcher.cs
@@ -12,11 +12,6 @@
 //  ----------------------------------------------------------------------------------
 namespace DurableTask.Core
 {
-    using System;
-    using System.Collections.Generic;
-    using System.Diagnostics;
-    using System.Threading;
-    using System.Threading.Tasks;
     using DurableTask.Core.Common;
     using DurableTask.Core.Entities;
     using DurableTask.Core.Entities.EventFormat;
@@ -27,6 +22,11 @@ namespace DurableTask.Core
     using DurableTask.Core.Middleware;
     using DurableTask.Core.Tracing;
     using Newtonsoft.Json;
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.Threading;
+    using System.Threading.Tasks;
 
     /// <summary>
     /// Dispatcher for orchestrations and entities to handle processing and renewing, completion of orchestration events.
@@ -182,7 +182,7 @@ async Task OnProcessWorkItemSessionAsync(TaskOrchestrationWorkItem workItem)
             }
         }
 
-        class WorkItemEffects
+        internal class WorkItemEffects
         {
             public List<TaskMessage> ActivityMessages;
             public List<TaskMessage> TimerMessages;
@@ -563,6 +563,9 @@ void DetermineWork(OrchestrationRuntimeState runtimeState, out SchedulerState sc
                         }
 
                         break;
+
+                    default:
+                        throw new EntitySchedulerException($"The entity with instanceId '{instanceId}' received an unexpected event type of type '{e.EventType}'. This is not a valid entity message. This is a framework-internal error, please report this issue in the GitHub repo: 'https://github.com/Azure/durabletask/'");
                 }
             }
 
@@ -791,7 +794,7 @@ void ProcessSendEventMessage(WorkItemEffects effects, OrchestrationInstance dest
             });
         }
 
-        void ProcessSendStartMessage(WorkItemEffects effects, OrchestrationRuntimeState runtimeState, StartNewOrchestrationOperationAction action)
+        internal void ProcessSendStartMessage(WorkItemEffects effects, OrchestrationRuntimeState runtimeState, StartNewOrchestrationOperationAction action)
         {
             OrchestrationInstance destination = new OrchestrationInstance()
             {
@@ -801,8 +804,8 @@ void ProcessSendStartMessage(WorkItemEffects effects, OrchestrationRuntimeState
             var executionStartedEvent = new ExecutionStartedEvent(-1, action.Input)
             {
                 Tags = OrchestrationTags.MergeTags(
-                    runtimeState.Tags,
-                    new Dictionary<string, string>() { { OrchestrationTags.FireAndForget, "" } }),
+                    newTags: new Dictionary<string, string>() { { OrchestrationTags.FireAndForget, "" } },
+                    existingTags: runtimeState.Tags),
                 OrchestrationInstance = destination,
                 ScheduledStartTime = action.ScheduledStartTime,
                 ParentInstance = new ParentInstance
@@ -881,4 +884,4 @@ await this.dispatchPipeline.RunAsync(dispatchContext, async _ =>
             return result;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/DurableTask.Emulator/LocalOrchestrationService.cs b/src/DurableTask.Emulator/LocalOrchestrationService.cs
index a8781df09..1331299ce 100644
--- a/src/DurableTask.Emulator/LocalOrchestrationService.cs
+++ b/src/DurableTask.Emulator/LocalOrchestrationService.cs
@@ -25,11 +25,12 @@ namespace DurableTask.Emulator
     using System.Text;
     using System.Threading;
     using System.Threading.Tasks;
+    using DurableTask.Core.Entities;
 
     /// <summary>
     /// Fully functional in-proc orchestration service for testing
     /// </summary>
-    public class LocalOrchestrationService : IOrchestrationService, IOrchestrationServiceClient, IDisposable
+    public class LocalOrchestrationService : IOrchestrationService, IOrchestrationServiceClient, IEntityOrchestrationService, IDisposable
     {
         // ReSharper disable once NotAccessedField.Local
         Dictionary<string, byte[]> sessionState;
@@ -669,5 +670,36 @@ void Dispose(bool disposing)
                 this.cancellationTokenSource.Dispose();
             }
         }
+
+        /// <inheritdoc />
+        /// Test only for core entities. The value is set as default.
+        EntityBackendProperties IEntityOrchestrationService.EntityBackendProperties => new EntityBackendProperties()
+        {
+            EntityMessageReorderWindow = TimeSpan.FromMinutes(30),
+            MaxEntityOperationBatchSize = null,
+            MaxConcurrentTaskEntityWorkItems = 100,
+            SupportsImplicitEntityDeletion = false, // not supported by this backend
+            MaximumSignalDelayTime = TimeSpan.FromDays(6),
+            UseSeparateQueueForEntityWorkItems = false,
+        };
+
+        /// <inheritdoc />
+        EntityBackendQueries IEntityOrchestrationService.EntityBackendQueries => null;
+
+        /// <inheritdoc />
+        Task<TaskOrchestrationWorkItem> IEntityOrchestrationService.LockNextEntityWorkItemAsync(
+            TimeSpan receiveTimeout,
+            CancellationToken cancellationToken)
+        {
+            return this.LockNextTaskOrchestrationWorkItemAsync(receiveTimeout, cancellationToken);
+        }
+
+        /// <inheritdoc />
+        Task<TaskOrchestrationWorkItem> IEntityOrchestrationService.LockNextOrchestrationWorkItemAsync(
+          TimeSpan receiveTimeout,
+          CancellationToken cancellationToken)
+        {
+            return this.LockNextTaskOrchestrationWorkItemAsync(receiveTimeout, cancellationToken);
+        }
     }
 }
diff --git a/test/DurableTask.SqlServer.Tests/DurableTask.SqlServer.Tests.csproj b/test/DurableTask.SqlServer.Tests/DurableTask.SqlServer.Tests.csproj
index cf578db09..e698b6266 100644
--- a/test/DurableTask.SqlServer.Tests/DurableTask.SqlServer.Tests.csproj
+++ b/test/DurableTask.SqlServer.Tests/DurableTask.SqlServer.Tests.csproj
@@ -23,7 +23,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="15.9.0" />
     <PackageReference Include="MSTest.TestAdapter" Version="1.3.2" />
     <PackageReference Include="MSTest.TestFramework" Version="1.3.2" />
-    <PackageReference Include="System.Data.SqlClient" Version="4.8.5" />
+    <PackageReference Include="System.Data.SqlClient" Version="4.8.6" />
   </ItemGroup>
 
   <ItemGroup>