The anti-forgery token could not be decrypted. 
If this application is hosted by a Web Farm or cluster,
ensure that all machines are running the same version of ASP.NET Web Pages and
that the <machineKey> configuration specifies explicit encryption and validation keys. 
AutoGenerate cannot be used in a cluster

Description: An unhandled exception occurred during the execution of the current web request. 
Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.Mvc.HttpAntiForgeryException: 
The anti-forgery token could not be decrypted.
If this application is hosted by a Web Farm or cluster, 
ensure that all machines are running the same version of ASP.NET Web Pages and that the <machineKey> configuration 
specifies explicit encryption and validation keys. AutoGenerate cannot be used in a cluster.

<system.web>
  <machineKey validationKey="mykey" decryptionKey="myotherkey" validation="SHA1" decryption="AES" />
</system.web>

Summary of Notable New Features in 15.9

• You can now import and export an installation configuration file that specifies which workloads and components should be installed with an instance of Visual Studio.
• We have improved the debugging experience for NuGet packages using the new symbol package format (.snupkg).
• Step back in debugger is now available in C++ for Enterprise customers.
• C++ IntelliSense now responds to changes in the remote environment for both CMake and MSBuild projects targeting Linux.
• We have made updates to UWP Desktop Bridge framework packages and added support for ARM64 C++ Native Desktop scenarios.
• We added support for the range-v3 library with the MSVC 15.9 compiler.
• We fixed several bugs in the F# compiler and F# tools.
• Language service support for new TypeScript features for semantic file renaming and project references.
• Improved Node.js development by updating Vue.js templates and adding support for unit testing using the Jest framework.
• We added SharePoint 2019 project templates, so you can migrate existing SharePoint 2013 and 2016 projects to SharePoint 2019.
• Visual Studio Tools for Xamarin now supports Xcode 10.
• We made improvements to the Xamarin.Android build performance.
• We have added and improved features for Universal Windows Platform developers, including ARM64 support, the latest preview SDK, better debugging of Desktop Bridge applications, and XAML Designer improvements.
• Substantial improvements were made to the experience of using authenticated package feeds.
• There is now support for lock file to enable repeatable restore for PackageReference based projects.
• We have added support for the new license format for NuGet packages.
• We have introduced NuGet client policies in Visual Studio which enables you to lock down environments such that only trusted packages can be installed.
• We made the use of .NET Core within Visual Studio more predictable.

Top Issues Fixed in 15.9

• No way to change "Find All References" background color.
• "Visual C++ Resource Editor Package" load failed.
• VS2017 v15.8 Build does not start if XAML files are not manually saved first.
• Installation failed - manifest signature verification failed.
• Update 15.8.6 breaks Installer Projects.
• Scrolling up with the arrow key causes Visual Studio to page up.
• After updating to 15.8.1, data tip does not show when debugging.
• System.InvalidProgramException: Common Language Runtime detected an invalid program..
• Solution Explorer does not remain pinned after closing Visual Studio.
• Navigation bar in editor has trouble handling long method names. 

SQL Server 2019 is designed to solve challenges of the modern data professional including:

• Store enterprise data in a data lake and offer SQL and Spark query capability overall data
• Reduce the need for Extract, Transform, and Load (ETL) applications by eliminating data movement
• Integrate and secure machine learning applications with scalable performance
• Reduce the need for application and query changes to gain a boost in performance
• Increase confidential computing of data through hardware enclaves
• Increase application and database uptime and availability through features like ADR (Advanced Database Recovery)
• Extend the power of the T-SQL language in a secure and robust fashion
• Run applications and deploy databases across multiple operating systems and platforms with compatibility
• Reduce the risk of upgrades while using new SQL capabilities when you are ready though inbuilt database compatibility levels 

{
  "jti": "b2921057-32a4-fbb2-0c18-5889c1ab8e70",
  "iss": "https://localhost:5001/",
  "iat": 1576402824,
  "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier": "1",
  "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name": "Vahid N.",
  "DisplayName": "Vahid N.",
  "http://schemas.microsoft.com/ws/2008/06/identity/claims/userdata": "1",
  "http://schemas.microsoft.com/ws/2008/06/identity/claims/role": "Admin",
  "nbf": 1576402824,
  "exp": 1576402944,
  "aud": "Any"
}

class App extends Component {
  state = {};

> npm install --save jwt-decode

import jwtDecode from "jwt-decode";
// ...

class App extends Component {
  state = {};

  componentDidMount() {
    try {
      const jwt = localStorage.getItem("token");
      const currentUser = jwtDecode(jwt);
      console.log("currentUser", currentUser);
      this.setState({ currentUser });
    } catch (ex) {
      console.log(ex);
    }
  }

  render() {
    return (
      <React.Fragment>
        <ToastContainer />
        <NavBar user={this.state.currentUser} />
        <main className="container">

const NavBar = ({ user }) => {

{!user && (
  <React.Fragment>
    <NavLink className="nav-item nav-link" to="/login">
      Login
    </NavLink>
    <NavLink className="nav-item nav-link" to="/register">
      Register
    </NavLink>
  </React.Fragment>
)}

{user && (
  <React.Fragment>
    <NavLink className="nav-item nav-link" to="/logout">
      Logout
    </NavLink>
    <NavLink className="nav-item nav-link" to="/profile">
      {user.DisplayName}
    </NavLink>
  </React.Fragment>
)}

this.props.history.push("/");

window.location = "/";

<NavLink className="nav-item nav-link" to="/logout">
   Logout
</NavLink>

import Logout from "./components/logout";
// ...

class App extends Component {
  render() {
    return (
          // ...
          <Switch>
            // ...
            <Route path="/logout" component={Logout} />

import { Component } from "react";

class Logout extends Component {
  componentDidMount() {
    localStorage.removeItem("token");
    window.location = "/";
  }

  render() {
    return null;
  }
}

export default Logout;

const tokenKey = "token";

export async function login(email, password) {
  const {
    data: { access_token }
  } = await http.post(apiEndpoint + "/login", { email, password });
  console.log("JWT", access_token);
  localStorage.setItem(tokenKey, access_token);
}

const { data } = this.state;
await auth.login(data.username, data.password);
window.location = "/";

export function logout() {
  localStorage.removeItem(tokenKey);
}

import * as auth from "../services/authService";

class Logout extends Component {
  componentDidMount() {
    auth.logout();

import jwtDecode from "jwt-decode";
//...

export function getCurrentUser() {
  try {
    const jwt = localStorage.getItem(tokenKey);
    const currentUser = jwtDecode(jwt);
    console.log("currentUser", currentUser);
    return currentUser;
  } catch (ex) {
    console.log(ex);
    return null;
  }
}

import * as auth from "./services/authService";

class App extends Component {
  state = {};

  componentDidMount() {
    const currentUser = auth.getCurrentUser();
    this.setState({ currentUser });
  }

export function loginWithJwt(jwt) {
   localStorage.setItem(tokenKey, jwt);
}

import * as auth from "../services/authService";
// ...
const response = await userService.register(this.state.data);
auth.loginWithJwt(response.headers["x-auth-token"]);

Ever wondered how JWT came to be and what problems it was designed to tackle? Are you curious about the plethora of algorithms available for signing and encrypting JWTs? Or are you interested in getting up-to-speed with JWTs as soon as possible? Then this handbook is for you. 

ConfuserEx is an free, open-source protector for .NET applications. It is the successor of Confuser project. 

Data fetching for React applications

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

What is GraphQL? 

GraphQL is a data querying language designed to describe the complex, nested data dependencies of modern applications. It's been in production use in Facebook's native apps for several years.