asp.net - The anti-forgery cookie token and form field token do not match in MVC 4

Question

I'm using the default login module in ASP.NET MVC 4. I did not change any code in the default application and i hosted it on a shared server.

After i logged in using default login page. i kept the browser idle for some time. Then obviously application redirected to the login page when i try to perform any controller action with [Authorize] attribute.

Then i try to login again and it gives an error when i click on login button.

The anti-forgery cookie token and form field token do not match.

LogIn action

// POST: /Account/Login

        [HttpPost]
        [AllowAnonymous]
        [ValidateAntiForgeryToken]
        public ActionResult Login(LoginModel model, string returnUrl)
        {
            if (ModelState.IsValid && WebSecurity.Login(model.UserName, model.Password, persistCookie: model.RememberMe))
            {
                return RedirectToLocal(returnUrl);
            }

            // If we got this far, something failed, redisplay form
            ModelState.AddModelError("", "The user name or password provided is incorrect.");
            return View(model);
        }

Answer 1

I resolved the issue by explicitly adding a machine key in web.config.

Note: For security reason don't use this key. Generate one from https://support.microsoft.com/en-us/kb/2915218#AppendixA. Dont use online-one, details, http://blogs.msdn.com/b/webdev/archive/2014/05/07/asp-net-4-5-2-and-enableviewstatemac.aspx

 <machineKey validationKey="971E32D270A381E2B5954ECB4762CE401D0DF1608CAC303D527FA3DB5D70FA77667B8CF3153CE1F17C3FAF7839733A77E44000B3D8229E6E58D0C954AC2E796B" decryptionKey="1D5375942DA2B2C949798F272D3026421DDBD231757CA12C794E68E9F8CECA71" validation="SHA1" decryption="AES" />

Here's a site that generates unique Machine Keys:

http://www.developerfusion.com/tools/generatemachinekey/