diff --git a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionCreated.cs b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionCreated.cs
index bd8b2b452..4638f7574 100644
--- a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionCreated.cs
+++ b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionCreated.cs
@@ -5,6 +5,13 @@ namespace Elsa.MassTransit.Messages;
 /// </summary>
 public class WorkflowDefinitionCreated(string id, bool usableAsActivity)
 {
-    public string Id { get; set; } = id;
-    public bool UsableAsActivity { get; set; } = usableAsActivity;
+    /// <summary>
+    /// The ID of the created workflow definition.
+    /// </summary>
+    public string Id { get; } = id;
+    
+    /// <summary>
+    /// Whether the created workflow definition is usable as an activity.
+    /// </summary>
+    public bool UsableAsActivity { get; } = usableAsActivity;
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionDeleted.cs b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionDeleted.cs
index bc3c286a1..ac7d54348 100644
--- a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionDeleted.cs
+++ b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionDeleted.cs
@@ -5,5 +5,8 @@ namespace Elsa.MassTransit.Messages;
 /// </summary>
 public class WorkflowDefinitionDeleted(string id)
 {
-    public string Id { get; set; } = id;
+    /// <summary>
+    /// The ID of the deleted workflow definition.
+    /// </summary>
+    public string Id { get; } = id;
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionPublished.cs b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionPublished.cs
index 86f219da1..9c77f2fc0 100644
--- a/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionPublished.cs
+++ b/src/modules/Elsa.MassTransit/Messages/WorkflowDefinitionPublished.cs
@@ -1,7 +1,17 @@
 namespace Elsa.MassTransit.Messages;
 
+/// <summary>
+/// Represents a distributed message that is triggered when a workflow definition is published.
+/// </summary>
 public class WorkflowDefinitionPublished(string id, bool usableAsActivity)
 {
-    public string Id { get; set; } = id;
-    public bool UsableAsActivity { get; set; } = usableAsActivity;
+    /// <summary>
+    /// The ID of the published workflow definition.
+    /// </summary>
+    public string Id { get; } = id;
+    
+    /// <summary>
+    /// Whether the published workflow definition is usable as an activity.
+    /// </summary>
+    public bool UsableAsActivity { get; } = usableAsActivity;
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Scheduling/Services/DefaultTriggerScheduler.cs b/src/modules/Elsa.Scheduling/Services/DefaultTriggerScheduler.cs
index 50735ab85..b626d72c0 100644
--- a/src/modules/Elsa.Scheduling/Services/DefaultTriggerScheduler.cs
+++ b/src/modules/Elsa.Scheduling/Services/DefaultTriggerScheduler.cs
@@ -91,7 +91,7 @@ public class DefaultTriggerScheduler(IWorkflowScheduler workflowScheduler, ISyst
             }
             catch (FormatException ex)
             {
-                logger.LogWarning($"Cron expression format error: {ex.Message}. CronExpression: {cronExpression}");
+                logger.LogWarning(ex,"Cron expression format error: {exceptionMessage}. CronExpression: {cronExpression}", ex.Message, cronExpression);
             }
         }
     }
diff --git a/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs b/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
index c8d77efbd..3af335fbe 100644
--- a/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
+++ b/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
@@ -5,6 +5,7 @@ using Elsa.Expressions.Models;
 using Elsa.Extensions;
 using Elsa.Workflows.Activities;
 using Elsa.Workflows.Contracts;
+using Elsa.Workflows.Exceptions;
 using Elsa.Workflows.Memory;
 using Elsa.Workflows.Models;
 using Elsa.Workflows.Options;
@@ -580,7 +581,7 @@ public partial class WorkflowExecutionContext : IExecutionContext
     /// </summary>
     public async Task<ActivityExecutionContext> CreateActivityExecutionContext(IActivity activity, ActivityInvocationOptions? options = default)
     {
-        var activityDescriptor = await ActivityRegistryLookup.Find(activity) ?? throw new Exception($"Activity with type {activity.Type} not found in registry");
+        var activityDescriptor = await ActivityRegistryLookup.Find(activity) ?? throw new ActivityNotFoundException(activity.Type);
         var tag = options?.Tag;
         var parentContext = options?.Owner;
         var parentExpressionExecutionContext = parentContext?.ExpressionExecutionContext ?? ExpressionExecutionContext;
diff --git a/src/modules/Elsa.Workflows.Core/Contracts/IActivityRegistry.cs b/src/modules/Elsa.Workflows.Core/Contracts/IActivityRegistry.cs
index c3ed1630f..4a7f44287 100644
--- a/src/modules/Elsa.Workflows.Core/Contracts/IActivityRegistry.cs
+++ b/src/modules/Elsa.Workflows.Core/Contracts/IActivityRegistry.cs
@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using Elsa.Workflows.Models;
 
 namespace Elsa.Workflows.Contracts;
@@ -74,7 +75,7 @@ public interface IActivityRegistry : IActivityProvider
     /// </summary>
     /// <param name="activityType">The activity type to register.</param>
     /// <param name="cancellationToken">An optional cancellation token.</param>
-    Task RegisterAsync(Type activityType, CancellationToken cancellationToken = default);
+    Task RegisterAsync([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] Type activityType, CancellationToken cancellationToken = default);
     
     /// <summary>
     /// Registers multiple activity types.
diff --git a/src/modules/Elsa.Workflows.Core/Exceptions/ActivityNotFoundException.cs b/src/modules/Elsa.Workflows.Core/Exceptions/ActivityNotFoundException.cs
index b7f2be040..caad78481 100644
--- a/src/modules/Elsa.Workflows.Core/Exceptions/ActivityNotFoundException.cs
+++ b/src/modules/Elsa.Workflows.Core/Exceptions/ActivityNotFoundException.cs
@@ -5,6 +5,12 @@ namespace Elsa.Workflows.Exceptions;
 /// </summary>
 public class ActivityNotFoundException : Exception
 {
+    /// <inheritdoc />
+    public ActivityNotFoundException(string missingTypeName) : base($"Activity type '{missingTypeName}' could not be found.")
+    {
+        MissingTypeName = missingTypeName;
+    }
+    
     /// <inheritdoc />
     public ActivityNotFoundException(string missingTypeName, int missingTypeVersion) : base($"Activity type '{missingTypeName}' version '{missingTypeVersion}' could not be found.")
     {
diff --git a/src/modules/Elsa.Workflows.Core/Services/ActivityRegistry.cs b/src/modules/Elsa.Workflows.Core/Services/ActivityRegistry.cs
index 8e596007b..beaea748f 100644
--- a/src/modules/Elsa.Workflows.Core/Services/ActivityRegistry.cs
+++ b/src/modules/Elsa.Workflows.Core/Services/ActivityRegistry.cs
@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using System.Diagnostics.CodeAnalysis;
 using Elsa.Workflows.Contracts;
 using Elsa.Workflows.Helpers;
 using Elsa.Workflows.Models;
@@ -48,7 +49,7 @@ public class ActivityRegistry(IActivityDescriber activityDescriber, IEnumerable<
     }
 
     /// <inheritdoc />
-    public async Task RegisterAsync(Type activityType, CancellationToken cancellationToken)
+    public async Task RegisterAsync([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] Type activityType, CancellationToken cancellationToken)
     {
         var activityTypeName = ActivityTypeNameHelper.GenerateTypeName(activityType);
 
@@ -70,6 +71,7 @@ public class ActivityRegistry(IActivityDescriber activityDescriber, IEnumerable<
     /// <inheritdoc />
     public ValueTask<IEnumerable<ActivityDescriptor>> GetDescriptorsAsync(CancellationToken cancellationToken = default) => new(_manualActivityDescriptors);
 
+    /// <inheritdoc />
     public async Task RefreshDescriptors(IEnumerable<IActivityProvider> activityProviders, CancellationToken cancellationToken = default)
     {
         var providersDictionary = new ConcurrentDictionary<Type, ICollection<ActivityDescriptor>>();
@@ -94,7 +96,7 @@ public class ActivityRegistry(IActivityDescriber activityDescriber, IEnumerable<
         Add(descriptor, _activityDescriptors, target);
     }
 
-    private void Add(ActivityDescriptor descriptor, ConcurrentDictionary<(string Type, int Version), ActivityDescriptor> activityDescriptors, ICollection<ActivityDescriptor> providerDescriptors)
+    private void Add(ActivityDescriptor? descriptor, ConcurrentDictionary<(string Type, int Version), ActivityDescriptor> activityDescriptors, ICollection<ActivityDescriptor> providerDescriptors)
     {
         if (descriptor is null)
         {
diff --git a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/AutoUpdateTests.cs b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/AutoUpdateTests.cs
index 040ff1726..8276dd1ff 100644
--- a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/AutoUpdateTests.cs
+++ b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/AutoUpdateTests.cs
@@ -3,7 +3,6 @@ using Elsa.Http;
 using Elsa.Http.Bookmarks;
 using Elsa.Http.Contracts;
 using Elsa.Workflows.Contracts;
-using Elsa.Workflows.Helpers;
 using Elsa.Workflows.Management.Contracts;
 using Elsa.Workflows.Runtime.Filters;
 using Microsoft.Extensions.Caching.Memory;
@@ -14,7 +13,6 @@ namespace Elsa.Workflows.ComponentTests.Scenarios.WorkflowActivities;
 public class AutoUpdateTests : AppComponentTest
 {
     private readonly IMemoryCache _cache;
-    private readonly IBookmarkHasher _bookmarkHasher;
     private readonly IHasher _hasher;
     private readonly IWorkflowDefinitionCacheManager _definitionCacheManager;
     private readonly IWorkflowDefinitionPublisher _publisher;
@@ -26,9 +24,9 @@ public class AutoUpdateTests : AppComponentTest
     private readonly IHttpWorkflowsCacheManager _httpCacheManager;
     private readonly IWorkflowDefinitionCacheManager _workflowCacheManager;
     
-    private string _httpChangeToken;
-    private string _triggerChangeToken;
-    private string _graphChangeToken;
+    private string? _httpChangeToken;
+    private string? _triggerChangeToken;
+    private string? _graphChangeToken;
     
     private static readonly object HttpChangeTokenSignal = new();
     private static readonly object TriggerChangeTokenSignal = new();
@@ -41,7 +39,6 @@ public class AutoUpdateTests : AppComponentTest
     public AutoUpdateTests(App app) : base(app)
     {
         _cache = Scope.ServiceProvider.GetRequiredService<IMemoryCache>();
-        _bookmarkHasher = Scope.ServiceProvider.GetRequiredService<IBookmarkHasher>();
         _hasher = Scope.ServiceProvider.GetRequiredService<IHasher>();
         _definitionCacheManager = Scope.ServiceProvider.GetRequiredService<IWorkflowDefinitionCacheManager>();
         _publisher = Scope.ServiceProvider.GetRequiredService<IWorkflowDefinitionPublisher>();
diff --git a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
index 249eab3fb..47949871c 100644
--- a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
+++ b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/DeleteWorkflowTests.cs
@@ -1,5 +1,4 @@
 using Elsa.Workflows.Contracts;
-using Elsa.Workflows.Management.Activities.WorkflowDefinitionActivity;
 using Elsa.Workflows.Management.Contracts;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -28,43 +27,42 @@ public class DeleteWorkflowTests : AppComponentTest
     [Fact]
     public async Task DeleteWorkflow()
     {
-        EnsureWorkflowInRegistry(_scope1);
+        EnsureWorkflowInRegistry(_scope1, Workflows.DeleteWorkflow.Type);
         
         var workflowDefinitionManager = _scope1.ServiceProvider.GetRequiredService<IWorkflowDefinitionManager>();
         await workflowDefinitionManager.DeleteByDefinitionIdAsync(Workflows.DeleteWorkflow.DefinitionId);
         
-        WorkflowTypeDeletedFromRegistry(_scope1);
+        WorkflowTypeDeletedFromRegistry(_scope1, Workflows.DeleteWorkflow.Type);
     }
     
     [Fact(Skip = "Clustered tests are interfering with other event driven tests")]
     public async Task DeleteWorkflow_Clustered()
     {
-        EnsureWorkflowInRegistry(_scope1);
-        EnsureWorkflowInRegistry(_scope2);
-        EnsureWorkflowInRegistry(_scope3);
+        EnsureWorkflowInRegistry(_scope1, Workflows.DeleteWorkflowClustered.Type);
+        EnsureWorkflowInRegistry(_scope2, Workflows.DeleteWorkflowClustered.Type);
+        EnsureWorkflowInRegistry(_scope3, Workflows.DeleteWorkflowClustered.Type);
         
         var workflowDefinitionManager = _scope1.ServiceProvider.GetRequiredService<IWorkflowDefinitionManager>();
-        await workflowDefinitionManager.DeleteByDefinitionIdAsync(Workflows.DeleteWorkflow.DefinitionId);
+        await workflowDefinitionManager.DeleteByDefinitionIdAsync(Workflows.DeleteWorkflowClustered.DefinitionId);
         
-        WorkflowTypeDeletedFromRegistry(_scope1);
+        WorkflowTypeDeletedFromRegistry(_scope1, Workflows.DeleteWorkflowClustered.Type);
         
         await _signalManager.WaitAsync<WorkflowDefinitionDeletedEventArgs>(WorkflowDeletedSignal);
-        WorkflowTypeDeletedFromRegistry(_scope2);
-        WorkflowTypeDeletedFromRegistry(_scope3);
+        WorkflowTypeDeletedFromRegistry(_scope2, Workflows.DeleteWorkflowClustered.Type);
+        WorkflowTypeDeletedFromRegistry(_scope3, Workflows.DeleteWorkflowClustered.Type);
     }
 
-    private void EnsureWorkflowInRegistry(IServiceScope scope)
+    private static void EnsureWorkflowInRegistry(IServiceScope scope, string type)
     {
         var activityRegistry = scope.ServiceProvider.GetRequiredService<IActivityRegistry>();
-        var descriptor = activityRegistry.Find(Workflows.DeleteWorkflow.Type);
-        if (descriptor is null)
-            activityRegistry.Add(typeof(WorkflowDefinitionActivityProvider), descriptor);
+        var descriptor = activityRegistry.Find(type);
+        Assert.NotNull(descriptor);
     }
 
-    private void WorkflowTypeDeletedFromRegistry(IServiceScope scope)
+    private static void WorkflowTypeDeletedFromRegistry(IServiceScope scope, string type)
     {
         var activityRegistry = scope.ServiceProvider.GetRequiredService<IActivityRegistry>();
-        var descriptor = activityRegistry.Find(Workflows.DeleteWorkflow.Type);
+        var descriptor = activityRegistry.Find(type);
 
         Assert.Null(descriptor);
     }
diff --git a/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/Workflows/DeleteWorkflow_Clustered.cs b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/Workflows/DeleteWorkflow_Clustered.cs
new file mode 100644
index 000000000..00b1722eb
--- /dev/null
+++ b/test/component/Elsa.Workflows.ComponentTests/Scenarios/WorkflowActivities/Workflows/DeleteWorkflow_Clustered.cs
@@ -0,0 +1,26 @@
+using Elsa.Scheduling.Activities;
+using Elsa.Workflows.Activities;
+using Elsa.Workflows.Contracts;
+
+namespace Elsa.Workflows.ComponentTests.Scenarios.WorkflowActivities.Workflows;
+
+public class DeleteWorkflowClustered : WorkflowBase
+{
+    public static readonly string DefinitionId = Guid.NewGuid().ToString(); 
+    public static readonly string Type = nameof(DeleteWorkflowClustered); 
+    
+    protected override void Build(IWorkflowBuilder builder)
+    {
+        builder.Name = Type;
+        builder.WithDefinitionId(DefinitionId);
+        builder.WorkflowOptions.UsableAsActivity = true;
+        builder.Root = new Sequence
+        {
+            Activities =
+            {
+                new Delay(TimeSpan.FromMilliseconds(250)),
+                new WriteLine("This workflow will be deleted!")
+            }
+        };
+    }
+}
\ No newline at end of file