diff --git a/src/clients/Elsa.Api.Client/Extensions/JsonObjectExtensions.cs b/src/clients/Elsa.Api.Client/Extensions/JsonObjectExtensions.cs
index 3653519b9..5b4ad7e9c 100644
--- a/src/clients/Elsa.Api.Client/Extensions/JsonObjectExtensions.cs
+++ b/src/clients/Elsa.Api.Client/Extensions/JsonObjectExtensions.cs
@@ -160,7 +160,7 @@ public static class JsonObjectExtensions
         {
             return model.GetProperty<T>(path);
         }
-        catch (Exception e)
+        catch (Exception)
         {
             return default;
         }
diff --git a/src/common/Elsa.Mediator/Contracts/ICommandSender.cs b/src/common/Elsa.Mediator/Contracts/ICommandSender.cs
index 5373afb3b..02d32ca7a 100644
--- a/src/common/Elsa.Mediator/Contracts/ICommandSender.cs
+++ b/src/common/Elsa.Mediator/Contracts/ICommandSender.cs
@@ -28,7 +28,7 @@ public interface ICommandSender
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <typeparam name="T">The type of the result.</typeparam>
     /// <returns>The result.</returns>
-    Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy strategy, CancellationToken cancellationToken = default);
+    Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy? strategy, CancellationToken cancellationToken = default);
 
     /// <summary>
     /// Sends a command using the specified strategy.
@@ -39,7 +39,7 @@ public interface ICommandSender
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <typeparam name="T">The type of the result.</typeparam>
     /// <returns>The result.</returns>
-    Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default);
+    Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy? strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default);
 
     /// <summary>
     /// Sends a command using the default strategy.
@@ -54,7 +54,7 @@ public interface ICommandSender
     /// <param name="command">The command to send.</param>
     /// <param name="strategy">The command strategy to use.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
-    Task SendAsync(ICommand command, ICommandStrategy strategy, CancellationToken cancellationToken = default);
+    Task SendAsync(ICommand command, ICommandStrategy? strategy, CancellationToken cancellationToken = default);
     
     /// <summary>
     /// Sends a command using the specified strategy.
@@ -63,5 +63,5 @@ public interface ICommandSender
     /// <param name="strategy">The command strategy to use.</param>
     /// <param name="headers">Any headers to pass along.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
-    Task SendAsync(ICommand command, ICommandStrategy strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default);
+    Task SendAsync(ICommand command, ICommandStrategy? strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default);
 }
\ No newline at end of file
diff --git a/src/common/Elsa.Mediator/Extensions/MediatorExtensions.cs b/src/common/Elsa.Mediator/Extensions/MediatorExtensions.cs
index e1b307658..69328381c 100644
--- a/src/common/Elsa.Mediator/Extensions/MediatorExtensions.cs
+++ b/src/common/Elsa.Mediator/Extensions/MediatorExtensions.cs
@@ -39,7 +39,7 @@ public static class MediatorExtensions
     /// <param name="cancellationToken">The cancellation token.</param>
     public static async Task SendAsync(this IMediator mediator, ICommand command, CancellationToken cancellationToken = default)
     {
-        await mediator.SendAsync(command, default, cancellationToken);
+        await mediator.SendAsync(command, null, cancellationToken);
     }
     
     /// <summary>
@@ -50,6 +50,6 @@ public static class MediatorExtensions
     /// <param name="cancellationToken">The cancellation token.</param>
     public static async Task SendAsync(this ICommandSender commandSender, ICommand command, CancellationToken cancellationToken = default)
     {
-        await commandSender.SendAsync(command, default, cancellationToken);
+        await commandSender.SendAsync(command, null, cancellationToken);
     }
 }
\ No newline at end of file
diff --git a/src/common/Elsa.Mediator/Services/DefaultMediator.cs b/src/common/Elsa.Mediator/Services/DefaultMediator.cs
index 3428e283f..96744ec57 100644
--- a/src/common/Elsa.Mediator/Services/DefaultMediator.cs
+++ b/src/common/Elsa.Mediator/Services/DefaultMediator.cs
@@ -54,9 +54,10 @@ public class DefaultMediator : IMediator
         return (T)context.Response;
     }
 
-    public async Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default)
+    public async Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy? strategy, IDictionary<object, object> headers, CancellationToken cancellationToken = default)
     {
         var resultType = typeof(T);
+        strategy ??= _defaultCommandStrategy;
         var context = new CommandContext(command, strategy, resultType, headers, _serviceProvider, cancellationToken);
         await _commandPipeline.InvokeAsync(context);
 
@@ -92,7 +93,7 @@ public class DefaultMediator : IMediator
     }
 
     /// <inheritdoc />
-    public Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy strategy, CancellationToken cancellationToken = default)
+    public Task<T> SendAsync<T>(ICommand<T> command, ICommandStrategy? strategy, CancellationToken cancellationToken = default)
     {
         return SendAsync(command, strategy, new Dictionary<object, object>(), cancellationToken);
     }
diff --git a/src/common/Elsa.Testing.Shared.Integration/DispatchWorkflowExtensions.cs b/src/common/Elsa.Testing.Shared.Integration/DispatchWorkflowExtensions.cs
index 578802abd..df3436068 100644
--- a/src/common/Elsa.Testing.Shared.Integration/DispatchWorkflowExtensions.cs
+++ b/src/common/Elsa.Testing.Shared.Integration/DispatchWorkflowExtensions.cs
@@ -63,7 +63,7 @@ public static class DispatchWorkflowExtensions
             var workflowDispatcher = serviceProvider.GetRequiredService<IWorkflowDispatcher>();
             var dispatchWorkflowResponse = await workflowDispatcher.DispatchAsync(new DispatchWorkflowDefinitionRequest
             {
-                DefinitionVersionId = workflow.DefinitionHandle.DefinitionVersionId,
+                DefinitionVersionId = workflow.DefinitionHandle.DefinitionVersionId!,
                 InstanceId = instanceId ?? Guid.NewGuid().ToString(),
             });
             dispatchWorkflowResponse.ThrowIfFailed();
diff --git a/src/common/Elsa.Testing.Shared/XunitLogger.cs b/src/common/Elsa.Testing.Shared/XunitLogger.cs
index 08c947157..e02d37fb5 100644
--- a/src/common/Elsa.Testing.Shared/XunitLogger.cs
+++ b/src/common/Elsa.Testing.Shared/XunitLogger.cs
@@ -3,33 +3,24 @@ using Xunit.Abstractions;
 
 namespace Elsa.Testing.Shared;
 
-public class XunitLogger : ILogger
+public class XunitLogger(ITestOutputHelper testOutputHelper, string categoryName) : ILogger
 {
-    private readonly ITestOutputHelper _testOutputHelper;
-    private readonly string _categoryName;
-
-    public XunitLogger(ITestOutputHelper testOutputHelper, string categoryName)
-    {
-        _testOutputHelper = testOutputHelper;
-        _categoryName = categoryName;
-    }
-
-    public IDisposable BeginScope<TState>(TState state) => NoopDisposable.Instance;
+    public IDisposable BeginScope<TState>(TState state) where TState : notnull => NoopDisposable.Instance;
 
     public bool IsEnabled(LogLevel logLevel)
         => true;
 
     public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
     {
-        _testOutputHelper.WriteLine($"{_categoryName} [{eventId}] {formatter(state, exception)}");
+        testOutputHelper.WriteLine($"{categoryName} [{eventId}] {formatter(state, exception)}");
 
         if (exception != null)
-            _testOutputHelper.WriteLine(exception.ToString());
+            testOutputHelper.WriteLine(exception.ToString());
     }
 
     private class NoopDisposable : IDisposable
     {
-        public static readonly NoopDisposable Instance = new NoopDisposable();
+        public static readonly NoopDisposable Instance = new();
 
         public void Dispose()
         {
diff --git a/src/modules/Elsa.Expressions.Liquid/Helpers/ConfigurationSectionWrapper.cs b/src/modules/Elsa.Expressions.Liquid/Helpers/ConfigurationSectionWrapper.cs
index 894e3d85e..3533f98d3 100644
--- a/src/modules/Elsa.Expressions.Liquid/Helpers/ConfigurationSectionWrapper.cs
+++ b/src/modules/Elsa.Expressions.Liquid/Helpers/ConfigurationSectionWrapper.cs
@@ -2,16 +2,9 @@
 
 namespace Elsa.Expressions.Liquid.Helpers;
 
-public class ConfigurationSectionWrapper
+public class ConfigurationSectionWrapper(IConfigurationSection section)
 {
-    private readonly IConfigurationSection _section;
+    public override string ToString() => section.Value!;
 
-    public ConfigurationSectionWrapper(IConfigurationSection section)
-    {
-        _section = section;
-    }
-
-    public override string ToString() => _section.Value;
-
-    public ConfigurationSectionWrapper GetSection(string name) => new(_section.GetSection(name));
+    public ConfigurationSectionWrapper GetSection(string name) => new(section.GetSection(name));
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Http/Activities/HttpEndpoint.cs b/src/modules/Elsa.Http/Activities/HttpEndpoint.cs
index 6b6590aac..c1a583ed5 100644
--- a/src/modules/Elsa.Http/Activities/HttpEndpoint.cs
+++ b/src/modules/Elsa.Http/Activities/HttpEndpoint.cs
@@ -461,7 +461,7 @@ public class HttpEndpoint : Trigger<HttpRequest>
         var contentType = httpRequest.ContentType!;
         var headers = httpRequest.Headers.ToDictionary(x => x.Key, x => x.Value.ToArray());
 
-        return await context.ParseContentAsync(contentStream, contentType, targetType, headers, cancellationToken);
+        return await context.ParseContentAsync(contentStream, contentType, targetType, headers!, cancellationToken);
     }
 
     private static bool HasContent(HttpRequest httpRequest) => httpRequest.Headers.ContentLength > 0;
diff --git a/src/modules/Elsa.Http/Activities/SendHttpRequestBase.cs b/src/modules/Elsa.Http/Activities/SendHttpRequestBase.cs
index 34e90abc7..bb8930ab5 100644
--- a/src/modules/Elsa.Http/Activities/SendHttpRequestBase.cs
+++ b/src/modules/Elsa.Http/Activities/SendHttpRequestBase.cs
@@ -240,8 +240,8 @@ public abstract class SendHttpRequestBase(string? source = null, int? line = nul
             _ => typeof(string)
         };
 
-        var contentHeadersDictionary = contentHeaders.ToDictionary(x => x.Key, x => x.Value.Cast<string?>().ToArray(), StringComparer.OrdinalIgnoreCase);
-        var responseHeadersDictionary = responseHeaders.ToDictionary(x => x.Key, x => x.Value.Cast<string?>().ToArray(), StringComparer.OrdinalIgnoreCase);
+        var contentHeadersDictionary = contentHeaders.ToDictionary(x => x.Key, x => x.Value.ToArray(), StringComparer.OrdinalIgnoreCase);
+        var responseHeadersDictionary = responseHeaders.ToDictionary(x => x.Key, x => x.Value.ToArray(), StringComparer.OrdinalIgnoreCase);
         var headersDictionary = contentHeadersDictionary.Concat(responseHeadersDictionary).ToDictionary(x => x.Key, x => x.Value, StringComparer.OrdinalIgnoreCase);
         return await context.ParseContentAsync(contentStream, contentType, targetType, headersDictionary, cancellationToken);
     }
diff --git a/src/modules/Elsa.Http/Activities/WriteHttpResponse.cs b/src/modules/Elsa.Http/Activities/WriteHttpResponse.cs
index 7b21e3353..2691cced5 100644
--- a/src/modules/Elsa.Http/Activities/WriteHttpResponse.cs
+++ b/src/modules/Elsa.Http/Activities/WriteHttpResponse.cs
@@ -101,7 +101,7 @@ public class WriteHttpResponse : Activity
         // Add headers.
         var headers = context.GetHeaders(ResponseHeaders);
         foreach (var header in headers)
-            response.Headers.Add(header.Key, header.Value);
+            response.Headers[header.Key] = header.Value;
 
         // Get content and content type.
         var content = context.Get(Content);
diff --git a/src/modules/Elsa.Http/ContentWriters/FormUrlEncodedHttpContentFactory.cs b/src/modules/Elsa.Http/ContentWriters/FormUrlEncodedHttpContentFactory.cs
index 5536181ea..ae4fc8539 100644
--- a/src/modules/Elsa.Http/ContentWriters/FormUrlEncodedHttpContentFactory.cs
+++ b/src/modules/Elsa.Http/ContentWriters/FormUrlEncodedHttpContentFactory.cs
@@ -20,7 +20,7 @@ public class FormUrlEncodedHttpContentFactory : IHttpContentFactory
             return dictionary.ToDictionary(x => x.Key, x => x.Value.ToString() ?? string.Empty);
 
         if (content is string or JsonObject)
-            return JsonSerializer.Deserialize<Dictionary<string, string>>(JsonSerializer.Serialize(content));
+            return JsonSerializer.Deserialize<Dictionary<string, string>>(JsonSerializer.Serialize(content))!;
 
         var jsonElement = JsonSerializer.SerializeToElement(content);
         return jsonElement.EnumerateObject().ToDictionary(x => x.Name, x => x.Value.ToString());
diff --git a/src/modules/Elsa.Http/Extensions/HttpActivityExecutionContextExtensions.cs b/src/modules/Elsa.Http/Extensions/HttpActivityExecutionContextExtensions.cs
index 3538ace13..85d45ff5e 100644
--- a/src/modules/Elsa.Http/Extensions/HttpActivityExecutionContextExtensions.cs
+++ b/src/modules/Elsa.Http/Extensions/HttpActivityExecutionContextExtensions.cs
@@ -8,7 +8,7 @@ namespace Elsa.Extensions;
 
 internal static class HttpActivityExecutionContextExtensions
 {
-    public static async Task<object?> ParseContentAsync(this ActivityExecutionContext context, Stream content, string contentType, Type? returnType, Dictionary<string, string?[]> headers, CancellationToken cancellationToken)
+    public static async Task<object?> ParseContentAsync(this ActivityExecutionContext context, Stream content, string contentType, Type? returnType, Dictionary<string, string[]> headers, CancellationToken cancellationToken)
     {
         var parsers = context.GetServices<IHttpContentParser>().OrderByDescending(x => x.Priority).ToList();
         var httpResponseParserContext = new HttpResponseParserContext(content, contentType, returnType, headers, cancellationToken);
diff --git a/src/modules/Elsa.Http/Handlers/UpdateRouteTable.cs b/src/modules/Elsa.Http/Handlers/UpdateRouteTable.cs
index 4d3571006..0ade01163 100644
--- a/src/modules/Elsa.Http/Handlers/UpdateRouteTable.cs
+++ b/src/modules/Elsa.Http/Handlers/UpdateRouteTable.cs
@@ -1,8 +1,6 @@
-using Elsa.Http.Options;
-using Elsa.Mediator.Contracts;
+using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Runtime.Notifications;
 using JetBrains.Annotations;
-using Microsoft.Extensions.Options;
 
 namespace Elsa.Http.Handlers;
 
@@ -10,7 +8,7 @@ namespace Elsa.Http.Handlers;
 /// A handler that updates the route table when workflow triggers and bookmarks are indexed.
 /// </summary>
 [UsedImplicitly]
-public class UpdateRouteTable(IRouteTableUpdater routeTableUpdater, IOptions<HttpActivityOptions> options) :
+public class UpdateRouteTable(IRouteTableUpdater routeTableUpdater) :
     INotificationHandler<WorkflowTriggersIndexed>,
     INotificationHandler<WorkflowBookmarksIndexed>
 {
diff --git a/src/modules/Elsa.Persistence.EFCore.Common/Extensions/BulkUpsertExtensions.cs b/src/modules/Elsa.Persistence.EFCore.Common/Extensions/BulkUpsertExtensions.cs
index 9f24898ea..fadf509a7 100644
--- a/src/modules/Elsa.Persistence.EFCore.Common/Extensions/BulkUpsertExtensions.cs
+++ b/src/modules/Elsa.Persistence.EFCore.Common/Extensions/BulkUpsertExtensions.cs
@@ -113,7 +113,7 @@ public static class BulkUpsertExtensions
                 var paramName = $"{{{parameterCount++}}}";
 
                 // If it's a shadow property, retrieve value via Entry(..).Property(..)
-                object? value = property.IsShadowProperty()
+                var value = property.IsShadowProperty()
                     ? dbContext.Entry(entity).Property(property.Name).CurrentValue
                     : property.PropertyInfo?.GetValue(entity);
 
@@ -176,7 +176,7 @@ public static class BulkUpsertExtensions
             {
                 var paramName = $"{{{parameterCount++}}}";
 
-                object? value = property.IsShadowProperty()
+                var value = property.IsShadowProperty()
                     ? dbContext.Entry(entity).Property(property.Name).CurrentValue
                     : property.PropertyInfo?.GetValue(entity);
 
@@ -185,7 +185,7 @@ public static class BulkUpsertExtensions
                     value = converter.ConvertToProvider(value);
 
                 placeholders.Add(paramName);
-                parameters.Add(value);
+                parameters.Add(value!);
             }
 
             sb.Append($"({string.Join(", ", placeholders)})");
@@ -238,7 +238,7 @@ public static class BulkUpsertExtensions
             {
                 var paramName = $"{{{parameterCount++}}}";
 
-                object? value = property.IsShadowProperty()
+                var value = property.IsShadowProperty()
                     ? dbContext.Entry(entity).Property(property.Name).CurrentValue
                     : property.PropertyInfo?.GetValue(entity);
 
@@ -255,7 +255,7 @@ public static class BulkUpsertExtensions
                 else
                     placeholders.Add(paramName);
                 
-                parameters.Add(value);
+                parameters.Add(value!);
             }
 
             sb.Append($"({string.Join(", ", placeholders)})");
@@ -308,7 +308,7 @@ public static class BulkUpsertExtensions
             {
                 var paramName = $"{{{parameterCount++}}}";
 
-                object? value = property.IsShadowProperty()
+                var value = property.IsShadowProperty()
                     ? dbContext.Entry(entity).Property(property.Name).CurrentValue
                     : property.PropertyInfo?.GetValue(entity);
 
@@ -317,7 +317,7 @@ public static class BulkUpsertExtensions
                     value = converter.ConvertToProvider(value);
 
                 placeholders.Add(paramName);
-                parameters.Add(value);
+                parameters.Add(value!);
             }
 
             sb.Append($"({string.Join(", ", placeholders)})");
@@ -374,7 +374,7 @@ public static class BulkUpsertExtensions
             {
                 var paramName = $"{{{parameterCount++}}}";
 
-                object? value = property.IsShadowProperty()
+                var value = property.IsShadowProperty()
                     ? dbContext.Entry(entity).Property(property.Name).CurrentValue
                     : property.PropertyInfo?.GetValue(entity);
 
@@ -382,7 +382,7 @@ public static class BulkUpsertExtensions
                 if (converter != null)
                     value = converter.ConvertToProvider(value);
 
-                parameters.Add(value);
+                parameters.Add(value!);
 
                 // Oracle aliases must match the column name
                 var alias = property.GetColumnName(storeObject);
diff --git a/src/modules/Elsa.Persistence.EFCore.Common/JsonValueComparer.cs b/src/modules/Elsa.Persistence.EFCore.Common/JsonValueComparer.cs
index 04fd79a67..db9d92238 100644
--- a/src/modules/Elsa.Persistence.EFCore.Common/JsonValueComparer.cs
+++ b/src/modules/Elsa.Persistence.EFCore.Common/JsonValueComparer.cs
@@ -13,7 +13,10 @@ namespace Elsa.Persistence.EFCore;
 /// For plain objects, fall back to deep equality comparison using JSON serialization
 /// (safe, but inefficient).
 /// </remarks>
-public class JsonValueComparer<T> : ValueComparer<T> {
+public class JsonValueComparer<T>() : ValueComparer<T>((t1, t2) => DoEquals(t1!, t2!),
+    t => DoGetHashCode(t),
+    t => DoGetSnapshot(t))
+{
 
     private static string Json(T instance) {
         return JsonSerializer.Serialize(instance);
@@ -24,9 +27,7 @@ public class JsonValueComparer<T> : ValueComparer<T> {
         if (instance is ICloneable cloneable)
             return (T)cloneable.Clone();
 
-        var result = (T)JsonSerializer.Deserialize<T>(Json(instance));
-        return result;
-
+        return JsonSerializer.Deserialize<T>(Json(instance))!;
     }
 
     private static int DoGetHashCode(T instance) {
@@ -43,15 +44,6 @@ public class JsonValueComparer<T> : ValueComparer<T> {
         if (left is IEquatable<T> equatable)
             return equatable.Equals(right);
 
-        var result = Json(left).Equals(Json(right));
-        return result;
-
+        return Json(left).Equals(Json(right));
     }
-
-    public JsonValueComparer() : base(
-        (t1, t2) => DoEquals(t1, t2), 
-        t => DoGetHashCode(t), 
-        t => DoGetSnapshot(t)) {
-    }
-
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Persistence.EFCore.Common/JsonValueConverterHelper.cs b/src/modules/Elsa.Persistence.EFCore.Common/JsonValueConverterHelper.cs
index d529731bf..6df4e4608 100644
--- a/src/modules/Elsa.Persistence.EFCore.Common/JsonValueConverterHelper.cs
+++ b/src/modules/Elsa.Persistence.EFCore.Common/JsonValueConverterHelper.cs
@@ -15,7 +15,7 @@ internal static class JsonValueConverterHelper
 
     public static string Serialize<T>(T obj) where T : class
     {
-        return (obj == null ? null : JsonSerializer.Serialize(obj, JsonSerializerOptions))!;
+        return (obj == null! ? null : JsonSerializer.Serialize(obj, JsonSerializerOptions))!;
     }
     
     private static JsonSerializerOptions CreateJsonSerializerOptions()
diff --git a/src/modules/Elsa.Persistence.EFCore/Modules/Management/WorkflowDefinitionStore.cs b/src/modules/Elsa.Persistence.EFCore/Modules/Management/WorkflowDefinitionStore.cs
index 203348715..7c2ffc896 100644
--- a/src/modules/Elsa.Persistence.EFCore/Modules/Management/WorkflowDefinitionStore.cs
+++ b/src/modules/Elsa.Persistence.EFCore/Modules/Management/WorkflowDefinitionStore.cs
@@ -221,7 +221,7 @@ public class EFCoreWorkflowDefinitionStore(EntityStore<ManagementElsaDbContext,
         if (filter.IsSystem != null)
             queryable = filter.IsSystem == true
                 ? queryable.Where(x => x.IsSystem == true)
-                : queryable.Where(x => x.IsSystem == false || x.IsSystem == null);
+                : queryable.Where(x => x.IsSystem == false || x.IsSystem == null!);
 
         if (filter.IsReadonly != null) queryable = queryable.Where(x => x.IsReadonly == filter.IsReadonly);
         return queryable;
diff --git a/src/modules/Elsa.Persistence.EFCore/Modules/Runtime/ActivityExecutionLogStore.cs b/src/modules/Elsa.Persistence.EFCore/Modules/Runtime/ActivityExecutionLogStore.cs
index f10ded7fd..c345550c0 100644
--- a/src/modules/Elsa.Persistence.EFCore/Modules/Runtime/ActivityExecutionLogStore.cs
+++ b/src/modules/Elsa.Persistence.EFCore/Modules/Runtime/ActivityExecutionLogStore.cs
@@ -6,7 +6,6 @@ using Elsa.Common.Codecs;
 using Elsa.Common.Entities;
 using Elsa.Extensions;
 using Elsa.Workflows;
-using Elsa.Workflows.Management.Options;
 using Elsa.Workflows.Runtime;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Extensions;
@@ -15,7 +14,6 @@ using Elsa.Workflows.Runtime.OrderDefinitions;
 using Elsa.Workflows.State;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore;
-using Microsoft.Extensions.Options;
 using Open.Linq.AsyncExtensions;
 
 namespace Elsa.Persistence.EFCore.Modules.Runtime;
@@ -26,10 +24,8 @@ namespace Elsa.Persistence.EFCore.Modules.Runtime;
 [UsedImplicitly]
 public class EFCoreActivityExecutionStore(
     EntityStore<RuntimeElsaDbContext, ActivityExecutionRecord> store,
-    ISafeSerializer safeSerializer,
     IPayloadSerializer payloadSerializer,
-    ICompressionCodecResolver compressionCodecResolver,
-    IOptions<ManagementOptions> options) : IActivityExecutionStore
+    ICompressionCodecResolver compressionCodecResolver) : IActivityExecutionStore
 {
     /// <inheritdoc />
     public async Task SaveAsync(ActivityExecutionRecord record, CancellationToken cancellationToken = default) => await store.SaveAsync(record, OnSaveAsync, cancellationToken);
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Export/Endpoint.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Export/Endpoint.cs
index 4f876a7ce..364696e9c 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Export/Endpoint.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowDefinitions/Export/Endpoint.cs
@@ -48,13 +48,14 @@ internal class Export : ElsaEndpoint<Request>
     {
         if (request.DefinitionId != null)
             await DownloadSingleWorkflowAsync(request.DefinitionId, request.VersionOptions, cancellationToken);
-        else
+        else if (request.Ids != null)
             await DownloadMultipleWorkflowsAsync(request.Ids, cancellationToken);
+        else await Send.NoContentAsync(cancellationToken);
     }
 
     private async Task DownloadMultipleWorkflowsAsync(ICollection<string> ids, CancellationToken cancellationToken)
     {
-        List<WorkflowDefinition> definitions = (await _store.FindManyAsync(new WorkflowDefinitionFilter
+        List<WorkflowDefinition> definitions = (await _store.FindManyAsync(new()
         {
             Ids = ids
         }, cancellationToken)).ToList();
@@ -88,7 +89,7 @@ internal class Export : ElsaEndpoint<Request>
     private async Task DownloadSingleWorkflowAsync(string definitionId, string? versionOptions, CancellationToken cancellationToken)
     {
         var parsedVersionOptions = string.IsNullOrEmpty(versionOptions) ? VersionOptions.Latest : VersionOptions.FromString(versionOptions);
-        WorkflowDefinition? definition = (await _store.FindManyAsync(new WorkflowDefinitionFilter
+        WorkflowDefinition? definition = (await _store.FindManyAsync(new()
         {
             DefinitionId = definitionId,
             VersionOptions = parsedVersionOptions
diff --git a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
index 718c0ca99..c8ad5401b 100644
--- a/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
+++ b/src/modules/Elsa.Workflows.Api/Endpoints/WorkflowInstances/List/Endpoint.cs
@@ -151,7 +151,7 @@ internal class List(IWorkflowInstanceStore store) : ElsaEndpoint<Request, Respon
                 {
                     var o = new WorkflowInstanceOrder<string>
                     {
-                        KeySelector = p => p.Name,
+                        KeySelector = p => p.Name!,
                         Direction = direction
                     };
 
diff --git a/src/modules/Elsa.Workflows.Api/Requirements/NotReadOnlyRequirement.cs b/src/modules/Elsa.Workflows.Api/Requirements/NotReadOnlyRequirement.cs
index 594896485..f11b00195 100644
--- a/src/modules/Elsa.Workflows.Api/Requirements/NotReadOnlyRequirement.cs
+++ b/src/modules/Elsa.Workflows.Api/Requirements/NotReadOnlyRequirement.cs
@@ -26,18 +26,19 @@ public class NotReadOnlyRequirementHandler : AuthorizationHandler<NotReadOnlyReq
     }
 
     /// <inheritdoc />
-    protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, NotReadOnlyRequirement requirement, NotReadOnlyResource resource)
+    protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, NotReadOnlyRequirement requirement, NotReadOnlyResource resource)
     {
         if (_managementOptions.Value.IsReadOnlyMode)
         {
-            context.Fail(new AuthorizationFailureReason(this, "Workflow edit is not allowed when the read-only mode is enabled."));
+            context.Fail(new(this, "Workflow edit is not allowed when the read-only mode is enabled."));
         }
 
         if (resource.WorkflowDefinition != null && (resource.WorkflowDefinition.IsReadonly || resource.WorkflowDefinition.IsSystem))
         {
-            context.Fail(new AuthorizationFailureReason(this, "Workflow edit is not allowed for a readonly or system workflow."));
+            context.Fail(new(this, "Workflow edit is not allowed for a readonly or system workflow."));
         }
 
         context.Succeed(requirement);
+        return Task.CompletedTask;
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs b/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
index febe80558..303b38aac 100644
--- a/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
+++ b/src/modules/Elsa.Workflows.Api/Serialization/ArgumentJsonConverter.cs
@@ -33,7 +33,7 @@ public class ArgumentJsonConverter : JsonConverter<ArgumentDefinition>
         var typeAlias = _wellKnownTypeRegistry.TryGetAlias(typeName, out var alias) ? alias : null;
         var isArray = typeName.IsArray;
         var isCollection = typeName.IsCollectionType();
-        var elementTypeName = isArray ? typeName.GetElementType() : isCollection ? typeName.GenericTypeArguments[0] : typeName;
+        var elementTypeName = isArray ? typeName.GetElementType()! : isCollection ? typeName.GenericTypeArguments[0] : typeName;
         var elementTypeAlias = _wellKnownTypeRegistry.GetAliasOrDefault(elementTypeName);
         var isAliasedArray = (isArray || isCollection) && typeAlias != null;
         var finalTypeAlias = isArray || isCollection ? typeAlias ?? elementTypeAlias : elementTypeAlias;
diff --git a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
index 274141172..9aa4c311c 100644
--- a/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
+++ b/src/modules/Elsa.Workflows.Core/Activities/ParallelForEachT.cs
@@ -90,7 +90,7 @@ public class ParallelForEach<T> : Activity
     private ICollection<Guid> GetTagList(ActivityExecutionContext context, string propertyName)
     {
         // Read the list of tags from the context using the specified property name. The value is stored as JsonArray, so we need to deserialize it.
-        var jsonArray = context.GetProperty<JsonArray>(propertyName);
+        var jsonArray = context.GetProperty<JsonArray>(propertyName)!;
         return jsonArray.Select(x => x.ConvertTo<Guid>()).ToList();
     }
     
diff --git a/src/modules/Elsa.Workflows.Core/Builders/WorkflowBuilder.cs b/src/modules/Elsa.Workflows.Core/Builders/WorkflowBuilder.cs
index b30d7669e..fd5608325 100644
--- a/src/modules/Elsa.Workflows.Core/Builders/WorkflowBuilder.cs
+++ b/src/modules/Elsa.Workflows.Core/Builders/WorkflowBuilder.cs
@@ -6,7 +6,7 @@ using Elsa.Workflows.Models;
 namespace Elsa.Workflows.Builders;
 
 /// <inheritdoc />
-public class WorkflowBuilder(IActivityVisitor activityVisitor, IIdentityGraphService identityGraphService, IActivityRegistry activityRegistry, IIdentityGenerator identityGenerator)
+public class WorkflowBuilder(IActivityVisitor activityVisitor, IIdentityGraphService identityGraphService, IActivityRegistry activityRegistry)
     : IWorkflowBuilder
 {
     /// <inheritdoc />
diff --git a/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs b/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
index fa1f67c30..33906c603 100644
--- a/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
+++ b/src/modules/Elsa.Workflows.Core/Contexts/WorkflowExecutionContext.cs
@@ -402,7 +402,7 @@ public partial class WorkflowExecutionContext : IExecutionContext
     /// <summary>
     /// The expression execution context for the current workflow execution.
     /// </summary>
-    public ExpressionExecutionContext? ExpressionExecutionContext { get; private set; }
+    public ExpressionExecutionContext ExpressionExecutionContext { get; private set; } = null!;
 
     /// <inheritdoc />
     public IEnumerable<Variable> Variables => Workflow.Variables;
diff --git a/src/modules/Elsa.Workflows.Core/Middleware/Activities/ExceptionHandlingMiddleware.cs b/src/modules/Elsa.Workflows.Core/Middleware/Activities/ExceptionHandlingMiddleware.cs
index b7028e2b8..e2237498c 100644
--- a/src/modules/Elsa.Workflows.Core/Middleware/Activities/ExceptionHandlingMiddleware.cs
+++ b/src/modules/Elsa.Workflows.Core/Middleware/Activities/ExceptionHandlingMiddleware.cs
@@ -1,4 +1,3 @@
-using Elsa.Common;
 using Elsa.Extensions;
 using Elsa.Workflows.Pipelines.ActivityExecution;
 using Microsoft.Extensions.Logging;
@@ -19,7 +18,7 @@ public static class ExceptionHandlingMiddlewareExtensions
 /// <summary>
 /// Catches any exceptions thrown by downstream components and transitions the workflow into the faulted state.
 /// </summary>
-public class ExceptionHandlingMiddleware(ActivityMiddlewareDelegate next, IIncidentStrategyResolver incidentStrategyResolver, ISystemClock systemClock, ILogger<ExceptionHandlingMiddleware> logger)
+public class ExceptionHandlingMiddleware(ActivityMiddlewareDelegate next, IIncidentStrategyResolver incidentStrategyResolver, ILogger<ExceptionHandlingMiddleware> logger)
     : IActivityExecutionMiddleware
 {
     /// <inheritdoc />
diff --git a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
index 00c49da52..838dae398 100644
--- a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
+++ b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverter.cs
@@ -4,7 +4,6 @@ using System.Reflection;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
-using Elsa.Expressions.Contracts;
 using Elsa.Extensions;
 using Elsa.Workflows.Serialization.ReferenceHandlers;
 using Newtonsoft.Json.Linq;
@@ -14,7 +13,7 @@ namespace Elsa.Workflows.Serialization.Converters;
 /// <summary>
 /// Reads objects as primitive types rather than <see cref="JsonElement"/> values while also maintaining the .NET type name for reconstructing the actual type.
 /// </summary>
-public class PolymorphicObjectConverter(IWellKnownTypeRegistry wellKnownTypeRegistry) : JsonConverter<object>
+public class PolymorphicObjectConverter : JsonConverter<object>
 {
     private const string TypePropertyName = "_type";
     private const string ItemsPropertyName = "_items";
@@ -77,7 +76,7 @@ public class PolymorphicObjectConverter(IWellKnownTypeRegistry wellKnownTypeRegi
         {
             var parsedModel = JsonElement.ParseValue(ref reader);
             var systemTextJson = parsedModel.GetProperty(IslandPropertyName).GetString();
-            return !string.IsNullOrWhiteSpace(systemTextJson) ? JsonObject.Parse(systemTextJson) : new JsonObject();
+            return !string.IsNullOrWhiteSpace(systemTextJson) ? JsonNode.Parse(systemTextJson)! : new JsonObject();
         }
 
         var isJsonArray = targetType == typeof(JsonArray);
@@ -86,7 +85,7 @@ public class PolymorphicObjectConverter(IWellKnownTypeRegistry wellKnownTypeRegi
         {
             var parsedModel = JsonElement.ParseValue(ref reader);
             var systemTextJson = parsedModel.GetProperty(IslandPropertyName).GetString();
-            return !string.IsNullOrWhiteSpace(systemTextJson) ? JsonArray.Parse(systemTextJson) : new JsonArray();
+            return !string.IsNullOrWhiteSpace(systemTextJson) ? JsonNode.Parse(systemTextJson)! : new JsonArray();
         }
 
         var isDictionary = typeof(IDictionary).IsAssignableFrom(targetType);
diff --git a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
index 4a8cdcb7e..2317a6372 100644
--- a/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
+++ b/src/modules/Elsa.Workflows.Core/Serialization/Converters/PolymorphicObjectConverterFactory.cs
@@ -51,6 +51,6 @@ public class PolymorphicObjectConverterFactory : JsonConverterFactory
         if (typeof(IDictionary<string, object>).IsAssignableFrom(typeToConvert))
             return new PolymorphicDictionaryConverter(options, _wellKnownTypeRegistry);
 
-        return new PolymorphicObjectConverter(_wellKnownTypeRegistry);
+        return new PolymorphicObjectConverter();
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Core/VariableStorageDrivers/WorkflowInstanceStorageDriver.cs b/src/modules/Elsa.Workflows.Core/VariableStorageDrivers/WorkflowInstanceStorageDriver.cs
index bb93720e3..469969041 100644
--- a/src/modules/Elsa.Workflows.Core/VariableStorageDrivers/WorkflowInstanceStorageDriver.cs
+++ b/src/modules/Elsa.Workflows.Core/VariableStorageDrivers/WorkflowInstanceStorageDriver.cs
@@ -33,7 +33,7 @@ public class WorkflowInstanceStorageDriver(IPayloadSerializer payloadSerializer,
             try
             {
                 var node = JsonSerializer.SerializeToNode(value);
-                dictionary[id] = node;
+                dictionary[id] = node!;
             }
             catch (Exception ex) when (ex is JsonException or NotSupportedException or ObjectDisposedException)
             {
diff --git a/src/modules/Elsa.Workflows.Management/Activities/WorkflowDefinitionActivity/WorkflowDefinitionActivity.cs b/src/modules/Elsa.Workflows.Management/Activities/WorkflowDefinitionActivity/WorkflowDefinitionActivity.cs
index e5f69bb47..e618ad467 100644
--- a/src/modules/Elsa.Workflows.Management/Activities/WorkflowDefinitionActivity/WorkflowDefinitionActivity.cs
+++ b/src/modules/Elsa.Workflows.Management/Activities/WorkflowDefinitionActivity/WorkflowDefinitionActivity.cs
@@ -125,6 +125,13 @@ public class WorkflowDefinitionActivity : Composite, IInitializable
         var serviceProvider = context.GetRequiredService<IServiceProvider>();
         var activityDescriptor = await FindActivityDescriptorAsync(serviceProvider);
 
+        if (activityDescriptor == null)
+        {
+            var logger = serviceProvider.GetRequiredService<ILogger<WorkflowDefinitionActivity>>();
+            logger.LogWarning("Could not find activity descriptor for activity type {ActivityType}", Type);
+            return;
+        }
+
         DeclareInputAsVariables(activityDescriptor, (descriptor, variable) =>
         {
             var inputName = descriptor.Name;
diff --git a/src/modules/Elsa.Workflows.Management/Mappers/VariableDefinitionMapper.cs b/src/modules/Elsa.Workflows.Management/Mappers/VariableDefinitionMapper.cs
index c1c3e491c..cd0bc53b7 100644
--- a/src/modules/Elsa.Workflows.Management/Mappers/VariableDefinitionMapper.cs
+++ b/src/modules/Elsa.Workflows.Management/Mappers/VariableDefinitionMapper.cs
@@ -81,7 +81,7 @@ public class VariableDefinitionMapper(IWellKnownTypeRegistry wellKnownTypeRegist
 
         var isArray = valueType.IsArray;
         var isCollection = valueType.IsCollectionType();
-        var elementValueType = isArray ? valueType.GetElementType() : isCollection ? valueType.GenericTypeArguments[0] : valueType;
+        var elementValueType = isArray ? valueType.GetElementType()! : isCollection ? valueType.GenericTypeArguments[0] : valueType;
         var elementTypeAlias = wellKnownTypeRegistry.GetAliasOrDefault(elementValueType);
 
         return new(source.Id, source.Name, elementTypeAlias, isArray, serializedValue, storageDriverTypeName);
diff --git a/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowDispatcher.cs b/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowDispatcher.cs
index 0a99360f1..19aca5c02 100644
--- a/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowDispatcher.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowDispatcher.cs
@@ -11,20 +11,20 @@ public interface IWorkflowDispatcher
     /// <summary>
     /// Dispatches a request to execute the specified workflow definition.
     /// </summary>
-    Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, DispatchWorkflowOptions options, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, DispatchWorkflowOptions? options, CancellationToken cancellationToken = default);
     
     /// <summary>
     /// Dispatches a request to execute the specified workflow instance.
     /// </summary>
-    Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, DispatchWorkflowOptions options, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, DispatchWorkflowOptions? options, CancellationToken cancellationToken = default);
     
     /// <summary>
     /// Starts all workflows and resumes existing workflow instances based on the specified activity type and bookmark payload.
     /// </summary>
-    Task<DispatchWorkflowResponse> DispatchAsync(DispatchTriggerWorkflowsRequest request, DispatchWorkflowOptions options, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowResponse> DispatchAsync(DispatchTriggerWorkflowsRequest request, DispatchWorkflowOptions? options, CancellationToken cancellationToken = default);
     
     /// <summary>
     /// Resumes the workflow waiting for the specified bookmark.
     /// </summary>
-    Task<DispatchWorkflowResponse> DispatchAsync(DispatchResumeWorkflowsRequest request, DispatchWorkflowOptions options, CancellationToken cancellationToken = default);
+    Task<DispatchWorkflowResponse> DispatchAsync(DispatchResumeWorkflowsRequest request, DispatchWorkflowOptions? options, CancellationToken cancellationToken = default);
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowExecutionLogStore.cs b/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowExecutionLogStore.cs
index 08bbe25cc..50a4767a0 100644
--- a/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowExecutionLogStore.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Contracts/IWorkflowExecutionLogStore.cs
@@ -15,11 +15,6 @@ public interface IWorkflowExecutionLogStore : ILogRecordStore<WorkflowExecutionL
     /// </summary>
     Task AddAsync(WorkflowExecutionLogRecord record, CancellationToken cancellationToken = default);
 
-    /// <summary>
-    /// Adds the specified set of <see cref="WorkflowExecutionLogRecord"/> objects to te persistence store.
-    /// </summary>
-    Task AddManyAsync(IEnumerable<WorkflowExecutionLogRecord> records, CancellationToken cancellationToken = default);
-
     /// <summary>
     /// Adds or updates the specified <see cref="WorkflowExecutionLogRecord"/> in the persistence store.
     /// </summary>
diff --git a/src/modules/Elsa.Workflows.Runtime/Features/WorkflowRuntimeFeature.cs b/src/modules/Elsa.Workflows.Runtime/Features/WorkflowRuntimeFeature.cs
index e5ab1d60f..501a67276 100644
--- a/src/modules/Elsa.Workflows.Runtime/Features/WorkflowRuntimeFeature.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Features/WorkflowRuntimeFeature.cs
@@ -17,7 +17,6 @@ using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Handlers;
 using Elsa.Workflows.Runtime.Options;
 using Elsa.Workflows.Runtime.Providers;
-using Elsa.Workflows.Runtime.Services;
 using Elsa.Workflows.Runtime.Stores;
 using Elsa.Workflows.Runtime.Tasks;
 using Elsa.Workflows.Runtime.UIHints;
diff --git a/src/modules/Elsa.Workflows.Runtime/Filters/TriggerFilter.cs b/src/modules/Elsa.Workflows.Runtime/Filters/TriggerFilter.cs
index cab0d7536..8435349aa 100644
--- a/src/modules/Elsa.Workflows.Runtime/Filters/TriggerFilter.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Filters/TriggerFilter.cs
@@ -69,7 +69,7 @@ public class TriggerFilter
         if (WorkflowDefinitionVersionId != null) queryable = queryable.Where(x => x.WorkflowDefinitionVersionId == WorkflowDefinitionVersionId);
         if (WorkflowDefinitionVersionIds != null) queryable = queryable.Where(x => WorkflowDefinitionVersionIds.Contains(x.WorkflowDefinitionVersionId));
         if (Name != null) queryable = queryable.Where(x => x.Name == Name);
-        if (Names != null) queryable = queryable.Where(x => Names.Contains(x.Name));
+        if (Names != null) queryable = queryable.Where(x => Names.Contains(x.Name!));
         if (Hash != null) queryable = queryable.Where(x => x.Hash == Hash);
         return queryable;
     }
diff --git a/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeDispatchWorkflowActivity.cs b/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeDispatchWorkflowActivity.cs
index 37b95583a..0b5046134 100644
--- a/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeDispatchWorkflowActivity.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Handlers/ResumeDispatchWorkflowActivity.cs
@@ -4,7 +4,6 @@ using Elsa.Workflows.Notifications;
 using Elsa.Workflows.Runtime.Activities;
 using Elsa.Workflows.Runtime.Stimuli;
 using JetBrains.Annotations;
-using Microsoft.Extensions.Logging;
 
 namespace Elsa.Workflows.Runtime.Handlers;
 
@@ -12,7 +11,7 @@ namespace Elsa.Workflows.Runtime.Handlers;
 /// Resumes any blocking <see cref="DispatchWorkflow"/> activities when its child workflow completes.
 /// </summary>
 [PublicAPI]
-internal class ResumeDispatchWorkflowActivity(IBookmarkQueue bookmarkQueue, IStimulusHasher stimulusHasher, ILogger<ResumeDispatchWorkflowActivity> logger) : INotificationHandler<WorkflowExecuted>
+internal class ResumeDispatchWorkflowActivity(IBookmarkQueue bookmarkQueue, IStimulusHasher stimulusHasher) : INotificationHandler<WorkflowExecuted>
 {
     private static readonly string ActivityTypeName = ActivityTypeNameHelper.GenerateTypeName<DispatchWorkflow>();
 
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/ObsoleteWorkflowRuntime.cs b/src/modules/Elsa.Workflows.Runtime/Services/ObsoleteWorkflowRuntime.cs
index f836f98a7..f317b7403 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/ObsoleteWorkflowRuntime.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/ObsoleteWorkflowRuntime.cs
@@ -67,7 +67,7 @@ public class ObsoleteWorkflowRuntime(
             TriggerActivityId = options?.TriggerActivityId
         };
         var response = await client.CreateAndRunInstanceAsync(createRequest, cancellationToken);
-        return new(response.WorkflowInstanceId, response.Status, response.SubStatus, response.Bookmarks, response.Incidents, null, null);
+        return new(response.WorkflowInstanceId, response.Status, response.SubStatus, response.Bookmarks, response.Incidents, null, new Dictionary<string, object>());
     }
 
     public async Task<ICollection<WorkflowExecutionResult>> StartWorkflowsAsync(string activityTypeName, object bookmarkPayload, TriggerWorkflowsOptions? options = null)
@@ -82,7 +82,7 @@ public class ObsoleteWorkflowRuntime(
             Input = options?.Input
         };
         var result = await stimulusSender.SendAsync(activityTypeName, bookmarkPayload, metadata, cancellationToken);
-        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, null)).ToList();
+        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, new Dictionary<string, object>())).ToList();
         return results;
     }
 
@@ -110,7 +110,7 @@ public class ObsoleteWorkflowRuntime(
 
         var response = await workflowClient.RunInstanceAsync(runWorkflowRequest, cancellationToken);
 
-        return new(response.WorkflowInstanceId, response.Status, response.SubStatus, response.Bookmarks, response.Incidents,null, null);
+        return new(response.WorkflowInstanceId, response.Status, response.SubStatus, response.Bookmarks, response.Incidents,null, new Dictionary<string, object>());
     }
 
     public async Task<ICollection<WorkflowExecutionResult>> ResumeWorkflowsAsync(string activityTypeName, object bookmarkPayload, TriggerWorkflowsOptions? options = null)
@@ -125,7 +125,7 @@ public class ObsoleteWorkflowRuntime(
             Input = options?.Input
         };
         var result = await stimulusSender.SendAsync(activityTypeName, bookmarkPayload, metadata, cancellationToken);
-        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, null)).ToList();
+        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, new Dictionary<string, object>())).ToList();
         return results;
     }
 
@@ -141,7 +141,7 @@ public class ObsoleteWorkflowRuntime(
             Input = options?.Input
         };
         var result = await stimulusSender.SendAsync(activityTypeName, bookmarkPayload, metadata, cancellationToken);
-        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, null)).ToList();
+        var results = result.WorkflowInstanceResponses.Select(x => new WorkflowExecutionResult(x.WorkflowInstanceId, x.Status, x.SubStatus, x.Bookmarks, x.Incidents, null, new Dictionary<string, object>())).ToList();
         return new(results);
     }
 
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/StimulusProxyWorkflowInbox.cs b/src/modules/Elsa.Workflows.Runtime/Services/StimulusProxyWorkflowInbox.cs
index 9a16af564..3a5d233aa 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/StimulusProxyWorkflowInbox.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/StimulusProxyWorkflowInbox.cs
@@ -182,7 +182,7 @@ public class StimulusProxyWorkflowInbox(
             new List<Bookmark>(),
             response.Incidents,
             null,
-            null)
+            new Dictionary<string, object>())
         );
     }
 }
\ No newline at end of file
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/StoreActivityExecutionLogSink.cs b/src/modules/Elsa.Workflows.Runtime/Services/StoreActivityExecutionLogSink.cs
index 72325955b..b3abf9795 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/StoreActivityExecutionLogSink.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/StoreActivityExecutionLogSink.cs
@@ -3,14 +3,13 @@ using Elsa.Mediator.Contracts;
 using Elsa.Workflows.Runtime.Entities;
 using Elsa.Workflows.Runtime.Notifications;
 
-namespace Elsa.Workflows.Runtime.Services;
+namespace Elsa.Workflows.Runtime;
 
 /// <summary>
 /// This implementation saves <see cref="ActivityExecutionRecord"/> directly through the store.
 /// </summary>
 public class StoreActivityExecutionLogSink(
     IActivityExecutionStore activityExecutionStore,
-    IActivityExecutionMapper mapper,
     INotificationSender notificationSender)
     : ILogRecordSink<ActivityExecutionRecord>
 {
diff --git a/src/modules/Elsa.Workflows.Runtime/Services/ValidatingWorkflowDispatcher.cs b/src/modules/Elsa.Workflows.Runtime/Services/ValidatingWorkflowDispatcher.cs
index 1126c3031..41361af8b 100644
--- a/src/modules/Elsa.Workflows.Runtime/Services/ValidatingWorkflowDispatcher.cs
+++ b/src/modules/Elsa.Workflows.Runtime/Services/ValidatingWorkflowDispatcher.cs
@@ -15,7 +15,7 @@ public class ValidatingWorkflowDispatcher(IWorkflowDispatcher decoratedService,
     private IWorkflowDispatcher DecoratedService { get; set; } = decoratedService;
 
     /// <inheritdoc />
-    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, DispatchWorkflowOptions? options = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowDefinitionRequest request, DispatchWorkflowOptions? options = null, CancellationToken cancellationToken = default)
     {
         if (!ValidateChannel(options?.Channel))
             return DispatchWorkflowResponse.UnknownChannel();
@@ -24,7 +24,7 @@ public class ValidatingWorkflowDispatcher(IWorkflowDispatcher decoratedService,
     }
 
     /// <inheritdoc />
-    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, DispatchWorkflowOptions? options = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchWorkflowInstanceRequest request, DispatchWorkflowOptions? options = null, CancellationToken cancellationToken = default)
     {
         if (!ValidateChannel(options?.Channel))
             return DispatchWorkflowResponse.UnknownChannel();
@@ -33,7 +33,7 @@ public class ValidatingWorkflowDispatcher(IWorkflowDispatcher decoratedService,
     }
 
     /// <inheritdoc />
-    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchTriggerWorkflowsRequest request, DispatchWorkflowOptions? options = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchTriggerWorkflowsRequest request, DispatchWorkflowOptions? options = null, CancellationToken cancellationToken = default)
     {
         if (!ValidateChannel(options?.Channel))
             return DispatchWorkflowResponse.UnknownChannel();
@@ -42,7 +42,7 @@ public class ValidatingWorkflowDispatcher(IWorkflowDispatcher decoratedService,
     }
 
     /// <inheritdoc />
-    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchResumeWorkflowsRequest request, DispatchWorkflowOptions? options = default, CancellationToken cancellationToken = default)
+    public async Task<DispatchWorkflowResponse> DispatchAsync(DispatchResumeWorkflowsRequest request, DispatchWorkflowOptions? options = null, CancellationToken cancellationToken = default)
     {
         if (!ValidateChannel(options?.Channel))
             return DispatchWorkflowResponse.UnknownChannel();
diff --git a/test/component/Elsa.Workflows.ComponentTests/Helpers/Activities/TriggerSignal.cs b/test/component/Elsa.Workflows.ComponentTests/Helpers/Activities/TriggerSignal.cs
index 66e936878..75efc701a 100644
--- a/test/component/Elsa.Workflows.ComponentTests/Helpers/Activities/TriggerSignal.cs
+++ b/test/component/Elsa.Workflows.ComponentTests/Helpers/Activities/TriggerSignal.cs
@@ -45,7 +45,7 @@ public class TriggerSignal : CodeActivity
     /// <inheritdoc />
     public TriggerSignal(Input<string> eventName, [CallerFilePath] string? source = null, [CallerLineNumber] int? line = null) : this(source, line) => EventName = eventName;
 
-    public Input<string> EventName { get; set; }
+    public Input<string> EventName { get; set; } = null!;
 
     protected override void Execute(ActivityExecutionContext context)
     {
diff --git a/test/component/Elsa.Workflows.ComponentTests/Scenarios/Activities/Composition/BulkDispatchWorkflows/BulkDispatchWorkflowsTests.cs b/test/component/Elsa.Workflows.ComponentTests/Scenarios/Activities/Composition/BulkDispatchWorkflows/BulkDispatchWorkflowsTests.cs
index 448fed7a8..34af7f849 100644
--- a/test/component/Elsa.Workflows.ComponentTests/Scenarios/Activities/Composition/BulkDispatchWorkflows/BulkDispatchWorkflowsTests.cs
+++ b/test/component/Elsa.Workflows.ComponentTests/Scenarios/Activities/Composition/BulkDispatchWorkflows/BulkDispatchWorkflowsTests.cs
@@ -127,7 +127,7 @@ public class BulkDispatchWorkflowsTests : AppComponentTest
         Assert.Equal(WorkflowSubStatus.Finished, result.WorkflowExecutionContext.SubStatus);
     }
 
-    private async Task<T> GetWorkflowVariableAsync<T>(TestWorkflowExecutionResult result, string variableName)
+    private async Task<T?> GetWorkflowVariableAsync<T>(TestWorkflowExecutionResult result, string variableName)
     {
         var variableManager = Scope.ServiceProvider.GetRequiredService<IWorkflowInstanceVariableManager>();
         var variables = await variableManager.GetVariablesAsync(result.WorkflowExecutionContext);
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/FlowchartNextActivity/Tests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/FlowchartNextActivity/Tests.cs
index 7a0fe6d1c..dd25a4f73 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/FlowchartNextActivity/Tests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/FlowchartNextActivity/Tests.cs
@@ -188,7 +188,7 @@ public class FlowchartNextActivityTests
         var result = await _workflowRunner.RunAsync(workflow);
         var lines = _capturingTextWriter.Lines.ToList();
         Assert.Equal(WorkflowSubStatus.Faulted, result.WorkflowState.SubStatus);
-        Assert.Equal(1, result.WorkflowState.Incidents.Count());
+        Assert.Single(result.WorkflowState.Incidents);
         Assert.Equal("Invalid backward connection: Every path from the source ('WriteLineE') must go through the target ('WriteLineC') when tracing back to the start.", result.WorkflowState.Incidents.First().Message);
         Assert.Equal(new[]
         {
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Incidents/IncidentStrategyTests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Incidents/IncidentStrategyTests.cs
index 9f82e7d03..ad8880b2c 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Incidents/IncidentStrategyTests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Incidents/IncidentStrategyTests.cs
@@ -30,6 +30,6 @@ public class IncidentStrategyTests
         var lines = _capturingTextWriter.Lines.ToList();
         Assert.Equal(expectedOutput, lines);
         Assert.Equal(expectedSubStatus, workflowState.SubStatus);
-        Assert.Equal(1, workflowState.Incidents.Count);
+        Assert.Single(workflowState.Incidents);
     }
 }
\ No newline at end of file
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Serialization/Tests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Serialization/Tests.cs
index 786c7a8ba..9c44a3efe 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Serialization/Tests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Scenarios/Serialization/Tests.cs
@@ -24,8 +24,8 @@ public class Tests
     public async Task Test1()
     {
         await _services.PopulateRegistriesAsync();
-        var workflowDefinition = _publisher.New();
-        var root = _serializer.Deserialize(workflowDefinition.StringData);
+        var workflowDefinition = await _publisher.NewAsync();
+        var root = _serializer.Deserialize(workflowDefinition.StringData!);
         Assert.NotNull(root);
     }
 }
\ No newline at end of file
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/ContainerSerialization/Tests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/ContainerSerialization/Tests.cs
index e3f2c9716..ae7af0a84 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/ContainerSerialization/Tests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/ContainerSerialization/Tests.cs
@@ -79,8 +79,8 @@ public class Tests
                 new(start, writeLine),
                 new(writeLine, end),
             },
+            RunAsynchronously = false
         };
-        container.RunAsynchronously = false;
 
         // Act
 
@@ -93,12 +93,11 @@ public class Tests
     }
 
     [Fact]
-    public async void SerializeSequenceContainerTest()
+    public async Task SerializeSequenceContainerTest()
     {
         await _services.PopulateRegistriesAsync();
 
         // Arrange
-
         var container = new Sequence
         {
             Id = "sequence",
@@ -127,9 +126,9 @@ public class Tests
                 { "int", 10 },
                 { "bool", false },
                 { "string", "str"},
-            }
+            },
+            RunAsynchronously = false
         };
-        container.RunAsynchronously = false;
 
         // Act
 
@@ -142,12 +141,11 @@ public class Tests
     }
 
     [Fact]
-    public async void SerializeParallelContainerTest()
+    public async Task SerializeParallelContainerTest()
     {
         await _services.PopulateRegistriesAsync();
 
         // Arrange
-
         var container = new Workflows.Activities.Parallel
         {
             Id = "parallel",
@@ -177,9 +175,9 @@ public class Tests
                 { "int", 10 },
                 { "bool", false },
                 { "string", "str"},
-            }
+            },
+            RunAsynchronously = false
         };
-        container.RunAsynchronously = false;
 
         // Act
 
@@ -199,10 +197,16 @@ public class Tests
         // Assert.Equivalent has trouble with the Behavior.Owner reference - since these aren't serialzied anyway, ignore them
         deserializedContainer.Behaviors.Clear();
         container.Behaviors.Clear();
-        foreach (Activity activity in deserializedContainer.Activities)
+        foreach (var activity1 in deserializedContainer.Activities)
+        {
+            var activity = (Activity)activity1;
             activity.Behaviors.Clear();
-        foreach (Activity activity in container.Activities)
+        }
+
+        foreach (var activity in container.Activities.Cast<Activity>())
+        {
             activity.Behaviors.Clear();
+        }
 
         // strict:false here allows "actual" to have extra public members that aren't part of "expected", and collection
         // comparison allows "actual" to have more data in it than is present in "expected".
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/JsonSerialization/Tests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/JsonSerialization/Tests.cs
index f4a853f28..e8e6343a9 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/JsonSerialization/Tests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/JsonSerialization/Tests.cs
@@ -158,7 +158,7 @@ public class SerializationTests(ITestOutputHelper testOutputHelper)
                 "StatusCode", "Created"
             },
             {
-                "Content", isArray ? (type == typeof(JArray) ? JArray.Parse(jsonContent) : JsonArray.Parse(jsonContent)) : (type == typeof(JObject) ? JObject.Parse(jsonContent) : JsonObject.Parse(jsonContent))
+                "Content", (isArray ? type == typeof(JArray) ? JArray.Parse(jsonContent) : JsonNode.Parse(jsonContent) : type == typeof(JObject) ? JObject.Parse(jsonContent) : JsonNode.Parse(jsonContent))!
             }
         };
         return dict;
diff --git a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/UIHintSerializiation/ActivityUIHintDescriberTests.cs b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/UIHintSerializiation/ActivityUIHintDescriberTests.cs
index 284d665c8..efcdc8e39 100644
--- a/test/integration/Elsa.Workflows.IntegrationTests/Serialization/UIHintSerializiation/ActivityUIHintDescriberTests.cs
+++ b/test/integration/Elsa.Workflows.IntegrationTests/Serialization/UIHintSerializiation/ActivityUIHintDescriberTests.cs
@@ -45,11 +45,11 @@ public class Tests
         var description = await activityDescriber.DescribeActivityAsync(typeof(TestActivity));
 
         var inputDescription = description.Inputs.First();
-        Assert.True(inputDescription.UISpecifications.ContainsKey(InputUIHints.DropDown));
+        Assert.True(inputDescription.UISpecifications!.ContainsKey(InputUIHints.DropDown));
         Assert.True(inputDescription.UISpecifications[InputUIHints.DropDown] is DropDownProps);
         var dropDownProperties = (DropDownProps) inputDescription.UISpecifications[InputUIHints.DropDown];
 
-        Assert.Collection(dropDownProperties.SelectList.Items,
+        Assert.Collection(dropDownProperties.SelectList!.Items,
             item => { Assert.Equal("OptionsAreNice", item.Text); Assert.Equal("OptionsAreNice", item.Value); },
             item => { Assert.Equal("ToHave", item.Text); Assert.Equal("ToHave", item.Value); },
             item => { Assert.Equal("IfYouCanChooseThem", item.Text); Assert.Equal("IfYouCanChooseThem", item.Value); });
diff --git a/test/performance/Elsa.Workflows.PerformanceTests/ConsoleActivitiesBenchmark.cs b/test/performance/Elsa.Workflows.PerformanceTests/ConsoleActivitiesBenchmark.cs
index 9f214cf1b..f8d6041fa 100644
--- a/test/performance/Elsa.Workflows.PerformanceTests/ConsoleActivitiesBenchmark.cs
+++ b/test/performance/Elsa.Workflows.PerformanceTests/ConsoleActivitiesBenchmark.cs
@@ -8,9 +8,9 @@ namespace Elsa.Workflows.PerformanceTests;
 [Config(typeof(Config))]
 public class ConsoleActivitiesBenchmark
 {
-    private WriteLine _writeLineWorkflow;
-    private IWorkflowRunner _workflowRunner;
-    private ServiceProvider _serviceProvider;
+    private WriteLine _writeLineWorkflow = null!;
+    private IWorkflowRunner _workflowRunner = null!;
+    private ServiceProvider _serviceProvider = null!;
 
     [GlobalSetup]
     public void GlobalSetup()
@@ -21,7 +21,7 @@ public class ConsoleActivitiesBenchmark
         _serviceProvider = services.BuildServiceProvider();
         _workflowRunner = _serviceProvider.GetRequiredService<IWorkflowRunner>();
         
-        _writeLineWorkflow = new WriteLine("Hello, World!");
+        _writeLineWorkflow = new("Hello, World!");
     }
     
     [Benchmark]
diff --git a/test/unit/Elsa.Activities.UnitTests/Composition/ExecuteWorkflowTests.cs b/test/unit/Elsa.Activities.UnitTests/Composition/ExecuteWorkflowTests.cs
index 1dd0a993c..c95c226a2 100644
--- a/test/unit/Elsa.Activities.UnitTests/Composition/ExecuteWorkflowTests.cs
+++ b/test/unit/Elsa.Activities.UnitTests/Composition/ExecuteWorkflowTests.cs
@@ -50,7 +50,7 @@ public class ExecuteWorkflowTests
                 opts.CorrelationId == DefaultCorrelationId &&
                 opts.Input != null && opts.Input.ContainsKey("Key1") && (string)opts.Input["Key1"] == "Value1" &&
                 opts.Input.ContainsKey("ParentInstanceId") && (string)opts.Input["ParentInstanceId"] == parentInstanceId &&
-                opts.Properties.ContainsKey("ParentInstanceId") && (string)opts.Properties["ParentInstanceId"] == parentInstanceId &&
+                opts.Properties!.ContainsKey("ParentInstanceId") && (string)opts.Properties["ParentInstanceId"] == parentInstanceId &&
                 (waitForCompletion ? opts.Properties.ContainsKey("WaitForCompletion") && (bool)opts.Properties["WaitForCompletion"] : !opts.Properties.ContainsKey("WaitForCompletion"))
             ),
             Arg.Any<CancellationToken>()
@@ -226,7 +226,7 @@ public class ExecuteWorkflowTests
         {
             Status = status,
             SubStatus = subStatus,
-            Output = output
+            Output = output ?? new Dictionary<string, object>()
         };
         var workflowResult = new RunWorkflowResult(null!, workflowState, workflow, null, Journal.Empty);