He subido mi sitio web a un alojamiento web y apareció este error;
'Se produjo un error durante una operación criptográfica.. '.

He investigado un poco y parece que la cookie formateada está vinculada a MachineKey (que difiere cuando se usa webhost).

He encontrado un método que debería solucionar este problema, pero el error persiste.

CÓDIGO:

/// <summary>
    /// This method removes a cookie if the machine key is different than the one that saved the cookie;
    /// </summary>
    protected void Application_Error(object sender, EventArgs e)
    {
        var error = Server.GetLastError();
        var cryptoEx = error as CryptographicException;
        if (cryptoEx != null)
        {
            FederatedAuthentication.WSFederationAuthenticationModule.SignOut();
            Global.Cookies.FormAuthenticated Cookie = new Global.Cookies.FormAuthenticated();
            Cookie.Delete();
            Server.ClearError();
        }
    }

STACKTRACE:

[CryptographicException: Error occurred during a cryptographic operation.]
   System.Web.Security.Cryptography.HomogenizingCryptoServiceWrapper.HomogenizeErrors(Func`2 func, Byte[] input) +115
   System.Web.Security.Cryptography.HomogenizingCryptoServiceWrapper.Unprotect(Byte[] protectedData) +59
   System.Web.Security.FormsAuthentication.Decrypt(String encryptedTicket) +9824926
   Archive_Template.Main.resolveLoginUser(String sessionKey) in f:\Archive_Template\Archive_Template\Main.aspx.cs:481
   Archive_Template.Main.OnPreInit(EventArgs e) in f:\Archive_Template\Archive_Template\Main.aspx.cs:52
   System.Web.UI.Page.PerformPreInit() +31
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +335