WebAuthorizer comes back authorized, but throws 401 when trying to parse users object

May 5, 2014 at 10:01 PM
I'm using LinqToTwitter to authorize a user to tweet in a ASP.NET C# Web Forms app. The process appears to work until the return from Twitter. Weirdly, the WebAuthorizer object (TwitterAuth) shows as authorized, but then when I call <code>users.SingleOrDefault</code>, an exception is thrown.

Here are the contents of the <code>users</code> object at the time <code>users.SingleOrDefault()</code> is called:
[0] = {value(LinqToTwitter.TwitterQueryable`1[LinqToTwitter.User])}
[1] = {tweet => ((Convert(tweet.Type) == 2) AndAlso (tweet.UserID == value(MyApp.TwitterConnect+<>c__DisplayClass4).twitterAuth.UserId))}
Here is the exception thrown:
Message = "Error while querying Twitter."
StackTrace = "  at LinqToTwitter.TwitterQueryProvider.Execute[TResult](Expression expression)\r\n   at System.Linq.Queryable.SingleOrDefault[TSource](IQueryable`1 source)\r\n   at MyApp.TwitterConnect.ReturnFromTwitter() in c:\\_code\\MyApp\\WebApps\\MyApp\\TwitterConnect.aspx.cs:line 115"
Here's the full InnerException of that, which I assume is more helpful:
{"The remote server returned an error: (401) Unauthorized."}
[System.Net.WebException]: {"The remote server returned an error: (401) Unauthorized."}
Data: {System.Collections.ListDictionaryInternal}
HelpLink: null
HResult: -2146233079
InnerException: null
Message: "The remote server returned an error: (401) Unauthorized."
Source: "LinqToTwitter"
StackTrace: "   at LinqToTwitter.TwitterExecute.QueryTwitter[T](Request request, IRequestProcessor`1 reqProc)"
TargetSite: {System.String QueryTwitter[T](LinqToTwitter.Request, LinqToTwitter.IRequestProcessor`1[T])}
Here is the (condensed and anonymized) relevant snippet of code:
private void ReturnFromTwitter()
    LinqToTwitter.TwitterContext twitterCtx;

    LinqToTwitter.IOAuthCredentials credentials = new LinqToTwitter.InMemoryCredentials();
    credentials.ConsumerKey = System.Configuration.ConfigurationManager.AppSettings["twitterConsumerKey"];
    credentials.ConsumerSecret = System.Configuration.ConfigurationManager.AppSettings["twitterConsumerSecret"];

    LinqToTwitter.WebAuthorizer twitterAuth = new LinqToTwitter.WebAuthorizer
        Credentials = credentials,
        PerformRedirect = authUrl => Response.Redirect(authUrl)

        string creds = twitterAuth.Credentials.ToString();

        if (twitterAuth.IsAuthorized)
            twitterCtx = new LinqToTwitter.TwitterContext(twitterAuth);

            var users =
                from tweet in twitterCtx.User
                where tweet.Type == LinqToTwitter.UserType.Show && tweet.UserID == twitterAuth.UserId
                select tweet;

            var user = users.SingleOrDefault(); //Exception is thrown here

            TwitterUID = long.Parse(user.UserID);
            TwitterOauthToken = twitterAuth.OAuthTwitter.OAuthToken;
            TwitterAccessToken = twitterAuth.Credentials.AccessToken;
            TwitterProfileImage = user.ProfileImageUrl;
            TwitterUserName = user.Name;
            IsConnected = false;
            Message = "Twitter is not properly connected...try again later.";
            //Log error
    catch (System.Exception ex)
        IsConnected = false;
        Message = "Unable to connect to Twitter...try again later.";
        //Log error
I have read this help document and confirmed that I am using the right consumer and secret keys. When I was in the portal, I didn't see any messages that our account was not in good standing. This code was working fine a couple of months ago, but then suddenly broke.

We are having a similar issue in the backend of our mobile apps (meaning the LinqToTwitter work is actually being done inside of web services). I know you recently modernized the library, but I've seen that updating necessitates significant code changes. I tried to implement these for the backend web services, but I wasn't able to (asynchronousness inside of APIs looks difficult or impossible, but that's beyond the scope here). Is the fact that we're using an outdated version ( of LinqToTwitter maybe responsible? Or does this sound like a different issue we could resolve without all those code changes?
May 6, 2014 at 1:58 PM

LINQ to Twitter v2.12, the last non-async version, is available as a download from this site. The FAQ, that I see you found, is currently the most accurate reference on how to resolve a 401 problem. As you can see, there could be many causes.