Asp.net 解密 Forms cookie 时出现加密操作期间出错

I've uploaded my website to a webhosting and this error came up;
'Error occurred during a cryptographic operation.'.

I've done some research and it seems that the formauthenticated cookie is bound to the MachineKey (which differs when using webhost).

I've found a method that should fix this problem but the error remains.

CODE:

/// <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