Membership.GetUser().ProviderUserKey always returns null

Question

I've recently started using ASP.NET Forms Authentication and Membership.

I created a C# project in Visual Studio, which automatically created pages like "/Account/Login.aspx".

I then followed an example for installing aspnet_* tables to my SQL Server database, and I've been able to use the <asp:CreateUserWizardStep> control to create a user.

I've then been able to login as this user, and the logged in username appears when calling <asp:LoginName>

However, when I call the following in my C# code, in a Button Click Event Handler, I always get a Null Reference Exception:

string UserID = Membership.GetUser().ProviderUserKey.ToString();

Shouldn't this return the UserID from my aspnet_users table?

If <asp:LoginName> is showing a UserName value, shouldn't I always be able to call Membership.GetUser().ProviderUserKey

_When_ do you call this? In the Logon code itself you will get `null` for the user. — H H, Aug 22 '11 at 11:38
You are definitely getting the `NullReferenceException` because the user object returned by `Membership.GetUser()` is `null`. So you should check for this before you ask for the `ProviderUserKey`. — Tim Schmelter, Aug 22 '11 at 12:51
@Henk Holterman I call it inside a Button Click Event Handler — Curtis, Aug 22 '11 at 13:44
@Tim Schmelter I appreciate this, but why? If `` is showing a UserName value, shouldn't I always be able to call `Membership.GetUser().ProviderUserKey`? — Curtis, Aug 22 '11 at 13:45
This answer [http://stackoverflow.com/a/15382691/285190](http://stackoverflow.com/a/15382691/285190) helped me. I knew I was missing something obvious `[InitializeSimpleMembership]` — Flexicoder, Jul 20 '13 at 14:29

Ofer Zelig · Accepted Answer · 2013-04-09T23:23:02.897

First check whether you have a valid authenticated user id. From your question, it sounds like you do have. But a series of checks is always a good practice.

I like to use these couple of methods (the second one calls the first, but you can also call the first one directly. I recommend calling the second one) which perform various checks and return a User ID or null if there is the user is not authenticated or unidentified:

    public static MembershipUser GetCurrentUser()
    {
        HttpContext httpContext = HttpContext.Current;
        if (httpContext != null && httpContext.User != null && httpContext.User.Identity.IsAuthenticated)
        {
            return Membership.GetUser();
        }

        return null;
    }

    /// <summary>
    /// Safe check of authenticity. Better than Request.IsAuthenticated in that if there's a used-to-be-valid cookie which does not correspond to the current database, it will fail safe
    /// </summary>
    /// <returns></returns>
    public static bool IsUserAuthenticated()
    {
        if (HttpContext.Current == null)
            return false;

        var request = HttpContext.Current.Request;

        if (!request.IsAuthenticated)
            return false;

        var membershipUser = GetCurrentUser();

        if (membershipUser != null)
            return true;

        return false;
    }

Membership.GetUser().ProviderUserKey always returns null

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