Update Abp-4_0.md

docs/en/Migration-Guides/Abp-4_0.md

@@ -1,5 +1,25 @@
 # ABP Framework 3.3 to 4.0 Migration Guide
 
+This document introduces the breaking changes done in the ABP Framework 4.0 and explains how to fix your 3.x based solutions while upgrading to the ABP Framework 4.0.
+
+> See this blog post (TODO: LINK) to learn what's new with the ABP Framework 4.0. This document only focuses on the breaking changes.
+
+## Overall
+
+Here, the overall list of the changes;
+
+* Upgraded to the .NET 5.0.
+* Upgraded to the Identity Server 4.1.1.
+* Moved from Newtonsoft.Json to System.Text.Json as the JSON serializer by default.
+* Made some API revisions & startup template changes for the Blazor UI.
+* Switched to `kebab-case` for conventional URLs for the auto API controller routes.
+* Removed the Angular Account Module Public UI (login, register... pages) since they are not being used in the default (authorization code) flow.
+* Moved retry logic for the Dynamic HTTP Client Proxies to the startup template.
+* Make read only for Creation audit properties of the entities.
+* TODO: Deprecate the SessionState in the @abp/ng.core package
+* TODO: Use IBrandingProvider in the Volo.Abp.UI package and remove the one in the Volo.Abp.AspNetCore.Mvc.UI.Theme.Shared
+* TODO: Change type of the IHasExtraProperties.ExtraProperties
+
 ## Auto API Controller Route Changes
 
 The route calculation for the [Auto API Controllers](https://docs.abp.io/en/abp/latest/API/Auto-API-Controllers) is changing with the ABP Framework version 4.0 ([#5325](https://github.com/abpframework/abp/issues/5325)). Before v4.0 the route paths were **camelCase**. After version 4.0, it's changed to **kebab-case** route paths where it is possible.
@@ -12,6 +32,16 @@ The route calculation for the [Auto API Controllers](https://docs.abp.io/en/abp/
 
 ![route-4](images/route-4.png)
 
+### How to Fix?
+
+You may not take any action for the MVC & Blazor UI projects.
+
+For the Angular UI, this change may effect your client UI. If you have used the [ABP CLI Service Proxy Generation](../UI/Angular/Service-Proxies.md), you can run the server side and re-generate the service proxies. If you haven't used this tool, you should manually update the related URLs in your application.
+
+If there are other type of clients (e.g. 3rd-party companies) using your APIs, they also need to update the URLs.
+
+### Use the v3.x style URLs
+
 If it is hard to change it in your application, you can still to use the version 3.x route strategy, by following one of the approaches;
 
 - Set `UseV3UrlStyle` to `true` in the options of the `options.ConventionalControllers.Create(...)` method. Example:
@@ -123,3 +153,7 @@ app.Use((httpContext, next) =>
 
 - `OpenEditModalAsync` method requires `EntityDto` instead of id (`Guid`) parameter.
 - `DeleteEntityAsync` method doesn't display confirmation dialog anymore. You can use the new `EntityActions` component in DataGrids to show confirmation messages. You can also inject `IUiMessageService` to your page or component and call `ConfirmAsync` explicitly.
+- TODO: Inconsistent Async suffix usage
+- TODO: Refactor namespaces for Blazor components
+- TODO: Update CreateGetListInputAsync on AbpCrudPageBase
+- TODO: Change app to div for app container in blazor UI