diff --git a/CQRS_Flow/.NET/Carts/Carts.Api.Tests/Carts/InitializingCart/InitializeCartTests.cs b/CQRS_Flow/.NET/Carts/Carts.Api.Tests/Carts/InitializingCart/InitializeCartTests.cs
index c13eb2e..5bf0613 100644
--- a/CQRS_Flow/.NET/Carts/Carts.Api.Tests/Carts/InitializingCart/InitializeCartTests.cs
+++ b/CQRS_Flow/.NET/Carts/Carts.Api.Tests/Carts/InitializingCart/InitializeCartTests.cs
@@ -21,7 +21,7 @@ public class InitCartFixture: ApiFixture<Startup>
 
         public override async Task InitializeAsync()
         {
-            CommandResponse = await Post(new InitializeCartRequest {ClientId = ClientId });
+            CommandResponse = await Post(new InitializeCartRequest(ClientId));
         }
     }
 
diff --git a/CQRS_Flow/.NET/Carts/Carts.Api/Carts.Api.csproj b/CQRS_Flow/.NET/Carts/Carts.Api/Carts.Api.csproj
index 75d93f1..4db8b29 100644
--- a/CQRS_Flow/.NET/Carts/Carts.Api/Carts.Api.csproj
+++ b/CQRS_Flow/.NET/Carts/Carts.Api/Carts.Api.csproj
@@ -9,12 +9,6 @@
     <ItemGroup>
         <PackageReference Include="Swashbuckle.AspNetCore" Version="6.1.4" />
         <PackageReference Include="Microsoft.AspNetCore.Mvc.NewtonsoftJson" Version="5.0.7" />
-        <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="5.0.7">
-          <PrivateAssets>all</PrivateAssets>
-          <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-        </PackageReference>
-        <PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.7" />
-        <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="5.0.7" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/CQRS_Flow/.NET/Carts/Carts.Api/Controllers/CartsController.cs b/CQRS_Flow/.NET/Carts/Carts.Api/Controllers/CartsController.cs
index 8f01706..992e751 100644
--- a/CQRS_Flow/.NET/Carts/Carts.Api/Controllers/CartsController.cs
+++ b/CQRS_Flow/.NET/Carts/Carts.Api/Controllers/CartsController.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Carts.Api.Requests.Carts;
 using Carts.Carts.GettingCartAtVersion;
 using Carts.Carts.GettingCartById;
@@ -27,19 +26,16 @@ public CartsController(
             IQueryBus queryBus,
             IIdGenerator idGenerator)
         {
-            Guard.Against.Null(commandBus, nameof(commandBus));
-            Guard.Against.Null(queryBus, nameof(queryBus));
-            Guard.Against.Null(idGenerator, nameof(idGenerator));
-
             this.commandBus = commandBus;
             this.queryBus = queryBus;
             this.idGenerator = idGenerator;
         }
 
         [HttpPost]
-        public async Task<IActionResult> InitializeCart([FromBody] InitializeCartRequest request)
+        public async Task<IActionResult> InitializeCart([FromBody] InitializeCartRequest? request)
         {
-            Guard.Against.Null(request, nameof(request));
+            if (request == null)
+                throw new ArgumentNullException(nameof(request));
 
             var cartId = idGenerator.New();
 
@@ -54,16 +50,16 @@ public async Task<IActionResult> InitializeCart([FromBody] InitializeCartRequest
         }
 
         [HttpPost("{id}/products")]
-        public async Task<IActionResult> AddProduct(Guid id, [FromBody] AddProductRequest request)
+        public async Task<IActionResult> AddProduct(Guid id, [FromBody] AddProductRequest? request)
         {
-            Guard.Against.Null(request, nameof(request));
-            Guard.Against.Null(request.ProductItem, nameof(request));
+            if (request == null)
+                throw new ArgumentNullException(nameof(request));
 
             var command = Carts.AddingProduct.AddProduct.Create(
                 id,
                 ProductItem.Create(
-                    request.ProductItem.ProductId,
-                    request.ProductItem.Quantity
+                    request.ProductItem?.ProductId,
+                    request.ProductItem?.Quantity
                 )
             );
 
@@ -73,17 +69,17 @@ public async Task<IActionResult> AddProduct(Guid id, [FromBody] AddProductReques
         }
 
         [HttpDelete("{id}/products")]
-        public async Task<IActionResult> RemoveProduct(Guid id, [FromBody] RemoveProductRequest request)
+        public async Task<IActionResult> RemoveProduct(Guid id, [FromBody] RemoveProductRequest? request)
         {
-            Guard.Against.Null(request, nameof(request));
-            Guard.Against.Null(request.ProductItem, nameof(request));
+            if (request == null)
+                throw new ArgumentNullException(nameof(request));
 
             var command = Carts.RemovingProduct.RemoveProduct.Create(
                 id,
                 PricedProductItem.Create(
-                    request.ProductItem.ProductId,
-                    request.ProductItem.Quantity,
-                    request.ProductItem.UnitPrice
+                    request.ProductItem?.ProductId,
+                    request.ProductItem?.Quantity,
+                    request.ProductItem?.UnitPrice
                 )
             );
 
@@ -124,9 +120,11 @@ public Task<IReadOnlyList<CartHistory>> GetHistory(Guid id)
         }
 
         [HttpGet("{id}/versions")]
-        public Task<CartDetails> GetVersion(Guid id, [FromQuery] GetCartAtVersion query)
+        public Task<CartDetails> GetVersion(Guid id, [FromQuery] GetCartAtVersion? query)
         {
-            Guard.Against.Null(query, nameof(query));
+            if (query == null)
+                throw new ArgumentNullException(nameof(query));
+
             return queryBus.Send<GetCartAtVersion, CartDetails>(GetCartAtVersion.Create(id, query.Version));
         }
     }
diff --git a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ConfirmCartRequest.cs b/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ConfirmCartRequest.cs
deleted file mode 100644
index 3c076b8..0000000
--- a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ConfirmCartRequest.cs
+++ /dev/null
@@ -1,9 +0,0 @@
-using System;
-
-namespace Carts.Api.Requests.Carts
-{
-    public class ConfirmCartRequest
-    {
-        public Guid CartId { get; set; }
-    }
-}
diff --git a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/InitializeCartRequest.cs b/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/InitializeCartRequest.cs
index 3510ceb..4de9a2f 100644
--- a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/InitializeCartRequest.cs
+++ b/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/InitializeCartRequest.cs
@@ -2,8 +2,7 @@
 
 namespace Carts.Api.Requests.Carts
 {
-    public class InitializeCartRequest
-    {
-        public Guid ClientId { get; set; }
-    }
+    public record InitializeCartRequest(
+        Guid? ClientId
+    );
 }
diff --git a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ProductItemRequest.cs b/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ProductItemRequest.cs
index 35e0b49..60b13e1 100644
--- a/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ProductItemRequest.cs
+++ b/CQRS_Flow/.NET/Carts/Carts.Api/Requests/Carts/ProductItemRequest.cs
@@ -2,10 +2,8 @@
 
 namespace Carts.Api.Requests.Carts
 {
-    public class ProductItemRequest
-    {
-        public Guid ProductId { get; set; }
-
-        public int Quantity { get;  set; }
-    }
+    public record ProductItemRequest(
+        Guid? ProductId,
+        int? Quantity
+    );
 }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts.csproj b/CQRS_Flow/.NET/Carts/Carts/Carts.csproj
index 3c1ee81..ca49ecd 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts.csproj
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts.csproj
@@ -13,7 +13,6 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="Ardalis.GuardClauses" Version="3.2.0" />
         <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" Version="5.0.0" />
     </ItemGroup>
 
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/AddProduct.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/AddProduct.cs
index 2192d7c..f17b8a7 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/AddProduct.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/AddProduct.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Carts.Carts.Products;
 using Carts.Pricing;
 using Core.Commands;
@@ -12,7 +11,6 @@ namespace Carts.Carts.AddingProduct
 {
     public class AddProduct: ICommand
     {
-
         public Guid CartId { get; }
 
         public ProductItem ProductItem { get; }
@@ -24,8 +22,8 @@ private AddProduct(Guid cartId, ProductItem productItem)
         }
         public static AddProduct Create(Guid cartId, ProductItem productItem)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Null(productItem, nameof(productItem));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new AddProduct(cartId, productItem);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/ProductAdded.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/ProductAdded.cs
index 1b22bcb..a5abb76 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/ProductAdded.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/AddingProduct/ProductAdded.cs
@@ -1,5 +1,4 @@
 using System;
-using Ardalis.GuardClauses;
 using Carts.Carts.Products;
 using Core.Events;
 
@@ -19,8 +18,8 @@ private ProductAdded(Guid cartId, PricedProductItem productItem)
 
         public static ProductAdded Create(Guid cartId, PricedProductItem productItem)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Null(productItem, nameof(productItem));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new ProductAdded(cartId, productItem);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/Cart.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/Cart.cs
index 26b8527..c189c50 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/Cart.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/Cart.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using Ardalis.GuardClauses;
 using Carts.Carts.AddingProduct;
 using Carts.Carts.ConfirmingCart;
 using Carts.Carts.InitializingCart;
@@ -31,7 +30,7 @@ public static Cart Initialize(
         }
 
         private Cart(){}
-        
+
         public override void When(object @event)
         {
             switch (@event)
@@ -79,9 +78,6 @@ public void AddProduct(
             IProductPriceCalculator productPriceCalculator,
             ProductItem productItem)
         {
-            Guard.Against.Null(productPriceCalculator, nameof(productPriceCalculator));
-            Guard.Against.Null(productItem, nameof(productItem));
-
             if(Status != CartStatus.Pending)
                 throw new InvalidOperationException($"Adding product for the cart in '{Status}' status is not allowed.");
 
@@ -116,8 +112,6 @@ private void Apply(ProductAdded @event)
         public void RemoveProduct(
             PricedProductItem productItemToBeRemoved)
         {
-            Guard.Against.Null(productItemToBeRemoved, nameof(productItemToBeRemoved));
-
             if(Status != CartStatus.Pending)
                 throw new InvalidOperationException($"Removing product from the cart in '{Status}' status is not allowed.");
 
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/Config.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/Config.cs
index dcea7e0..c558011 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/Config.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/Config.cs
@@ -22,9 +22,8 @@ internal static class CartsConfig
     {
         internal static void AddCarts(this IServiceCollection services)
         {
-            services.AddScoped<IProductPriceCalculator, RandomProductPriceCalculator>();
-
-            services.AddScoped<IRepository<Cart>, EventStoreDBRepository<Cart>>();
+            services.AddScoped<IProductPriceCalculator, RandomProductPriceCalculator>()
+                    .AddScoped<IRepository<Cart>, EventStoreDBRepository<Cart>>();
 
             AddCommandHandlers(services);
             AddProjections(services);
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/CartConfirmed.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/CartConfirmed.cs
index d5be9cf..ef6474a 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/CartConfirmed.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/CartConfirmed.cs
@@ -1,18 +1,27 @@
 using System;
-using Ardalis.GuardClauses;
 using Core.Events;
 
 namespace Carts.Carts.ConfirmingCart
 {
-    public record CartConfirmed(
-        Guid CartId,
-        DateTime ConfirmedAt
-    ): IEvent
+    public class CartConfirmed: IEvent
     {
+        public Guid CartId { get; }
+
+        public DateTime ConfirmedAt { get; }
+
+        public CartConfirmed(Guid cartId, DateTime confirmedAt)
+        {
+            CartId = cartId;
+            ConfirmedAt = confirmedAt;
+        }
+
         public static CartConfirmed Create(Guid cartId, DateTime confirmedAt)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Default(confirmedAt, nameof(confirmedAt));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
+
+            if(confirmedAt == DateTime.MinValue || confirmedAt == DateTime.MaxValue)
+                throw new ArgumentOutOfRangeException(nameof(confirmedAt));
 
             return new CartConfirmed(cartId, confirmedAt);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/ConfirmCart.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/ConfirmCart.cs
index f5eb862..e96f87a 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/ConfirmCart.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/ConfirmingCart/ConfirmCart.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Core.Commands;
 using Core.Repositories;
 using MediatR;
@@ -19,7 +18,8 @@ private ConfirmCart(Guid cartId)
 
         public static ConfirmCart Create(Guid cartId)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new ConfirmCart(cartId);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartAtVersion/GetCartAtVersion.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartAtVersion/GetCartAtVersion.cs
index 51b9a0b..bc57666 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartAtVersion/GetCartAtVersion.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartAtVersion/GetCartAtVersion.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Carts.Carts.GettingCartById;
 using Core.EventStoreDB.Events;
 using Core.Exceptions;
@@ -23,7 +22,8 @@ private GetCartAtVersion(Guid cartId, ulong version)
 
         public static GetCartAtVersion Create(Guid cartId, ulong version)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new GetCartAtVersion(cartId, version);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartById/GetCartById.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartById/GetCartById.cs
index da41091..de35cd1 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartById/GetCartById.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartById/GetCartById.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Core.ElasticSearch.Indices;
 using Core.Exceptions;
 using Core.Queries;
@@ -20,7 +19,8 @@ private GetCartById(Guid cartId)
 
         public static GetCartById Create(Guid cartId)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new GetCartById(cartId);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartHistory/GetCartHistory.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartHistory/GetCartHistory.cs
index c63eb82..6abd6fd 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartHistory/GetCartHistory.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCartHistory/GetCartHistory.cs
@@ -3,13 +3,12 @@
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Core.Queries;
 using Nest;
 
 namespace Carts.Carts.GettingCartHistory
 {
-    public class GetCartHistory : IQuery<IReadOnlyList<CartHistory>>
+    public class GetCartHistory: IQuery<IReadOnlyList<CartHistory>>
     {
         public Guid CartId { get; }
         public int PageNumber { get; }
@@ -24,14 +23,16 @@ private GetCartHistory(Guid cartId, int pageNumber, int pageSize)
 
         public static GetCartHistory Create(Guid cartId, int pageNumber = 1, int pageSize = 20)
         {
-            Guard.Against.NegativeOrZero(pageNumber, nameof(pageNumber));
-            Guard.Against.NegativeOrZero(pageSize, nameof(pageSize));
+            if (pageNumber <= 0)
+                throw new ArgumentOutOfRangeException(nameof(pageNumber));
+            if (pageSize is <= 0 or > 100)
+                throw new ArgumentOutOfRangeException(nameof(pageSize));
 
             return new GetCartHistory(cartId, pageNumber, pageSize);
         }
     }
 
-    internal class HandleGetCartHistory :
+    internal class HandleGetCartHistory:
         IQueryHandler<GetCartHistory, IReadOnlyList<CartHistory>>
     {
         private readonly IElasticClient elasticClient;
@@ -56,4 +57,4 @@ public async Task<IReadOnlyList<CartHistory>> Handle(GetCartHistory request,
             return result.Documents.ToList();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCarts/GetCarts.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCarts/GetCarts.cs
index c76eb6d..326f05b 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCarts/GetCarts.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/GettingCarts/GetCarts.cs
@@ -1,8 +1,8 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Core.Queries;
 using Nest;
 
@@ -21,8 +21,10 @@ private GetCarts(int pageNumber, int pageSize)
 
         public static GetCarts Create(int pageNumber = 1, int pageSize = 20)
         {
-            Guard.Against.NegativeOrZero(pageNumber, nameof(pageNumber));
-            Guard.Against.NegativeOrZero(pageSize, nameof(pageSize));
+            if (pageNumber <= 0)
+                throw new ArgumentOutOfRangeException(nameof(pageNumber));
+            if (pageSize is <= 0 or > 100)
+                throw new ArgumentOutOfRangeException(nameof(pageSize));
 
             return new GetCarts(pageNumber, pageSize);
         }
@@ -50,4 +52,4 @@ public async Task<IReadOnlyList<CartShortInfo>> Handle(GetCarts request,
             return result.Documents.ToList();
         }
     }
-}
\ No newline at end of file
+}
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/CartInitialized.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/CartInitialized.cs
index c443228..6f75578 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/CartInitialized.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/CartInitialized.cs
@@ -1,5 +1,4 @@
 using System;
-using Ardalis.GuardClauses;
 using Core.Events;
 
 namespace Carts.Carts.InitializingCart
@@ -21,9 +20,12 @@ public CartInitialized(Guid cartId, Guid clientId, CartStatus cartStatus)
 
         public static CartInitialized Create(Guid cartId, Guid clientId, CartStatus cartStatus)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Default(clientId, nameof(clientId));
-            Guard.Against.Default(cartStatus, nameof(cartStatus));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
+            if (clientId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(clientId));
+            if (cartStatus == default)
+                throw new ArgumentOutOfRangeException(nameof(cartStatus));
 
             return new CartInitialized(cartId, clientId, cartStatus);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/InitializeCart.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/InitializeCart.cs
index bd51f8c..a4c380a 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/InitializeCart.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/InitializingCart/InitializeCart.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Ardalis.GuardClauses;
 using Core.Commands;
 using Core.Repositories;
 using MediatR;
@@ -20,12 +19,14 @@ private InitializeCart(Guid cartId, Guid clientId)
             ClientId = clientId;
         }
 
-        public static InitializeCart Create(Guid cartId, Guid clientId)
+        public static InitializeCart Create(Guid? cartId, Guid? clientId)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Default(clientId, nameof(clientId));
+            if (!cartId.HasValue|| cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
+            if (!clientId.HasValue || clientId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(clientId));
 
-            return new InitializeCart(cartId, clientId);
+            return new InitializeCart(cartId.Value, clientId.Value);
         }
     }
 
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/Products/PricedProductItem.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/Products/PricedProductItem.cs
index 9218e8f..8601848 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/Products/PricedProductItem.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/Products/PricedProductItem.cs
@@ -68,5 +68,22 @@ public bool HasTheSameQuantity(PricedProductItem pricedProductItem)
         {
             return ProductItem.HasTheSameQuantity(pricedProductItem.ProductItem);
         }
+
+        public override bool Equals(object? obj)
+        {
+            if (ReferenceEquals(null, obj)) return false;
+            if (ReferenceEquals(this, obj)) return true;
+            return obj.GetType() == GetType() && Equals((PricedProductItem) obj);
+        }
+
+        private bool Equals(PricedProductItem other)
+        {
+            return UnitPrice == other.UnitPrice && ProductItem.Equals(other.ProductItem);
+        }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(UnitPrice, ProductItem);
+        }
     }
 }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/Products/ProductItem.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/Products/ProductItem.cs
index dd036ff..da136d4 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/Products/ProductItem.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/Products/ProductItem.cs
@@ -57,5 +57,22 @@ public bool HasTheSameQuantity(ProductItem productItem)
         {
             return Quantity == productItem.Quantity;
         }
+
+        public override bool Equals(object? obj)
+        {
+            if (ReferenceEquals(null, obj)) return false;
+            if (ReferenceEquals(this, obj)) return true;
+            return obj.GetType() == GetType() && Equals((ProductItem) obj);
+        }
+
+        private bool Equals(ProductItem other)
+        {
+            return ProductId.Equals(other.ProductId) && Quantity == other.Quantity;
+        }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(ProductId, Quantity);
+        }
     }
 }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Carts/RemovingProduct/ProductRemoved.cs b/CQRS_Flow/.NET/Carts/Carts/Carts/RemovingProduct/ProductRemoved.cs
index dde793b..80dc029 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Carts/RemovingProduct/ProductRemoved.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Carts/RemovingProduct/ProductRemoved.cs
@@ -1,5 +1,4 @@
 using System;
-using Ardalis.GuardClauses;
 using Carts.Carts.Products;
 using Core.Events;
 
@@ -19,8 +18,8 @@ public ProductRemoved(Guid cartId, PricedProductItem productItem)
 
         public static ProductRemoved Create(Guid cartId, PricedProductItem productItem)
         {
-            Guard.Against.Default(cartId, nameof(cartId));
-            Guard.Against.Null(productItem, nameof(productItem));
+            if (cartId == Guid.Empty)
+                throw new ArgumentOutOfRangeException(nameof(cartId));
 
             return new ProductRemoved(cartId, productItem);
         }
diff --git a/CQRS_Flow/.NET/Carts/Carts/Pricing/RandomProductPriceCalculator.cs b/CQRS_Flow/.NET/Carts/Carts/Pricing/RandomProductPriceCalculator.cs
index cd75526..6a511f7 100644
--- a/CQRS_Flow/.NET/Carts/Carts/Pricing/RandomProductPriceCalculator.cs
+++ b/CQRS_Flow/.NET/Carts/Carts/Pricing/RandomProductPriceCalculator.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using Ardalis.GuardClauses;
 using Carts.Carts.Products;
 
 namespace Carts.Pricing
@@ -10,7 +9,8 @@ public class RandomProductPriceCalculator: IProductPriceCalculator
     {
         public IReadOnlyList<PricedProductItem> Calculate(params ProductItem[] productItems)
         {
-            Guard.Against.Zero(productItems.Length, "Product items count");
+            if (productItems.Length == 0)
+                throw new ArgumentOutOfRangeException(nameof(productItems), "Product items cannot be an empty");
 
             var random = new Random();
 
diff --git a/CQRS_Flow/.NET/ECommerce.sln b/CQRS_Flow/.NET/ECommerce.sln
index 70994c7..4bf9e33 100644
--- a/CQRS_Flow/.NET/ECommerce.sln
+++ b/CQRS_Flow/.NET/ECommerce.sln
@@ -27,6 +27,11 @@ ProjectSection(SolutionItems) = preProject
 	docker-compose.yml = docker-compose.yml
 EndProjectSection
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "docs", "docs", "{A33F3671-D99D-47A0-A584-16D444A2C238}"
+ProjectSection(SolutionItems) = preProject
+	README.md = README.md
+EndProjectSection
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
diff --git a/CQRS_Flow/.NET/README.md b/CQRS_Flow/.NET/README.md
index abcc5e1..833f60c 100644
--- a/CQRS_Flow/.NET/README.md
+++ b/CQRS_Flow/.NET/README.md
@@ -47,7 +47,7 @@ It uses:
 - Added hosted service [SubscribeToAllBackgroundWorker](./Core/Core.EventStoreDB/Subscriptions/SubscribeToAllBackgroundWorker.cs) to handle subscribing to all. It handles checkpointing and simple retries if the connection was dropped.
 - Added [ISubscriptionCheckpointRepository](./Core/Core.EventStoreDB/Subscriptions/ISubscriptionCheckpointRepository.cs) for handling Subscription checkpointing.
 - Added checkpointing to EventStoreDB stream with [EventStoreDBSubscriptionCheckpointRepository](./Core/Core.EventStoreDB/Subscriptions/EventStoreDBSubscriptionCheckpointRepository.cs) and dummy in-memory checkpointer [InMemorySubscriptionCheckpointRepository](./Core/Core.EventStoreDB/Subscriptions/InMemorySubscriptionCheckpointRepository.cs),
-- Added [ElasticSearchProjection](./Core/Core.ElasticSearch/Projections/ElasticSearchProjection.cs) as a sample how to project with [`left-fold`](https://en.wikipedia.org/wiki/Fold_(higher-order_function)) into external storage. Another (e.g. ElasticSearch, EntityFramework) can be implemented the same way.
+- Added [ElasticSearchProjection](./Core/Core.ElasticSearch/Projections/ElasticSearchProjection.cs) as a sample how to project with [`left-fold`](https://en.wikipedia.org/wiki/Fold_(higher-order_function)) into external storage. Another (e.g. MongoDB, EntityFramework) can be implemented the same way.
 
 ## Tests
 - Added sample of unit testing in [`Carts.Tests`](./Carts/Carts.Tests):
diff --git a/CQRS_Flow/.NET/docker-compose.yml b/CQRS_Flow/.NET/docker-compose.yml
index 090709e..5d23dbb 100644
--- a/CQRS_Flow/.NET/docker-compose.yml
+++ b/CQRS_Flow/.NET/docker-compose.yml
@@ -4,13 +4,13 @@ services:
   #  EventStoreDB - Event Store
   #######################################################
   eventstore.db:
-    image: eventstore/eventstore:21.2.0-buster-slim
+    image: eventstore/eventstore:21.6.0-buster-slim
     environment:
       - EVENTSTORE_CLUSTER_SIZE=1
       - EVENTSTORE_RUN_PROJECTIONS=All
       - EVENTSTORE_START_STANDARD_PROJECTIONS=true
       - EVENTSTORE_EXT_TCP_PORT=1113
-      - EVENTSTORE_EXT_HTTP_PORT=2113
+      - EVENTSTORE_HTTP_PORT=2113
       - EVENTSTORE_INSECURE=true
       - EVENTSTORE_ENABLE_EXTERNAL_TCP=true
       - EVENTSTORE_ENABLE_ATOM_PUB_OVER_HTTP=true