Signalr assembly loading issue OWIN

Question

I'm getting this error when attempting to load classes in the Microsoft.AspNet.SignalR.Owin assembly.

The exception is thrown after execution leaves the Configurationmethod in startup.cs. I've registered a Global Exception Handler to try and catch the exception but it is not being caught.

public async override Task HandleAsync(ExceptionHandlerContext context, CancellationToken cancellationToken)
        {

            var exception = context.Exception;

            const string genericErrorMessage =  "An unexpected error occured";
            var response = context.Request.CreateResponse(HttpStatusCode.InternalServerError,
                new
                {
                    Message = genericErrorMessage
                });

            response.Headers.Add("X - Error & ", genericErrorMessage);
            context.Result = new ResponseMessageResult(response);
        }

config.Services.Replace(typeof(IExceptionHandler), new GlobalExceptionHandler());

the Application_Error method in Global.asax doesn't catch it either

 protected void Application_Error(object sender, EventArgs e)
    {
        HttpContext ctx = HttpContext.Current;
        KeyValuePair<string, object> error = new KeyValuePair<string, object>("ErrorMessage", ctx.Server.GetLastError().ToString());
        ctx.Response.Clear();
    }

I've tried reinstalling the assembly but to no avail.

There's two other questions on SO but no solutions

Despite configuring Visual studio to break on every possible type of exception, this is still not being caught. The only place i can tell an exception has occurred is in the output window. Nothing is logged to the event logs.

For info this is using VS 2015

SignalR.ReflectedHubDescriptorProvider Warning: 0 : Some of the classes from assembly "Microsoft.AspNet.SignalR.Owin, Version=1.2.2.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" could Not be loaded when searching for Hubs. [...\Microsoft.AspNet.SignalR.Owin.dll]

Original exception type: ReflectionTypeLoadException

Original exception message: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information.

EDIT: I'm running all the latest Signalr packages

Installed signalr related packages

Autofac.SignalR v 3.0.2

Microsoft.AspNet.SignalR v2.2.0

Microsoft.AspNet.SignalR.Core v2.2.0

Microsoft.AspNet.SignalR.JS v2.2.0

Microsoft.AspNet.SignalR.Owin v1.2.2

Microsoft.AspNet.SignalR.SelfHost v2.2.0

Microsoft.AspNet.SignalR.SystemWeb v2.2.0

You might want to search for the original exception message on Google. There are many suggestions — Rick S, Sep 15 '15 at 16:37
https://www.google.com/search?q=Unable+to+load+one+or+more+of+the+requested+types.+Retrieve+the+LoaderExceptions+property+for+more+information.&oq=Unable+to+load+one+or+more+of+the+requested+types.+Retrieve+the+LoaderExceptions+property+for+more+information.&aqs=chrome..69i57.703j0j7&sourceid=chrome&es_sm=93&ie=UTF-8 — Rick S, Sep 15 '15 at 17:49
Have you retrieved the loader exceptions? They will give you additional hints as to what is wrong. — flq, Sep 22 '15 at 19:00
Problem is the error occurs somewhere in the pipeline after exiting the Configuration Method in Startup.cs and my GlobalException Handler isn't catching it. — MrBliz, Sep 22 '15 at 19:25
Unfortunate... I just caused a `EntryPointNotFoundException - No assembly found containing an OwinStartupAttribute` and found detailed stack trace under `Event Viewer/Windows Logs/Application`. — jsanalytics, Sep 23 '15 at 13:26
Absolutely nothing. The application startups fine, it's just that the signalr components don't work. — MrBliz, Sep 23 '15 at 13:28
Have you tried to catch the exception using `Global.asax`, `Application_Error(object sender, EventArgs e)` method? — jsanalytics, Sep 23 '15 at 13:43
Suggestion: Go to `Debug/Windows/Exception Settings` and configure it to break in all exceptions. — jsanalytics, Sep 23 '15 at 14:45
Whenever it breaks, keep hitting `Continue` and it will cycle through any exceptions — jsanalytics, Sep 23 '15 at 14:53
Cheers, every exception type is ticked, but it still isn't caught. Driving me mad! :) — MrBliz, Sep 23 '15 at 14:54
How did you see the `Original exception type: ReflectionTypeLoadException` ? — jsanalytics, Sep 23 '15 at 14:56
With the new settings, does it break in this exception now? Or do you still need to go to the Output window to see it? — jsanalytics, Sep 23 '15 at 14:59
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/90450/discussion-between-mrbliz-and-jstreet). — MrBliz, Sep 23 '15 at 15:00
Do you have the two dependencies installed as described here: [Microsoft ASP.NET SignalR OWIN 1.2.2](https://www.nuget.org/packages/Microsoft.AspNet.SignalR.Owin/1.2.2) ? — jsanalytics, Sep 23 '15 at 21:27
Dependencies are `Microsoft.AspNet.SignalR.Core (≥ 1.2.2)` and `Owin (≥ 1.0)` — jsanalytics, Sep 23 '15 at 21:30
Did you try to re-install using `Install-Package Microsoft.AspNet.SignalR.Owin` ? — jsanalytics, Sep 23 '15 at 21:36
Off-topic: Any reason why you can't use SignalR version > 2? — Aditya Santoso, Sep 24 '15 at 02:20
`Microsoft.AspNet.SignalR.Owin 1.2.2` is the latest stable version on NuGet. — jsanalytics, Sep 24 '15 at 09:05
I've uninstalled and reinstalled all signalr packages many times. — MrBliz, Sep 24 '15 at 12:33
In your project references, do you have `Owin` and `Microsoft.Owin` ? — jsanalytics, Sep 24 '15 at 14:54
Now I'm just wondering: does your program work fine despite this exception, or is it affecting proper execution? — jsanalytics, Sep 24 '15 at 16:19
The web site runs fine, apart from the bits that require SignalR. Exceution isn't broken, it's just that the clients don't get the updates. It's possible that the error i'm seeing isn't the problem that's causing the signalr parts of the site to fail, but i need to eliminate that possibility. — MrBliz, Sep 24 '15 at 16:23
Created a new project, and no longer get the error, but it seems this problem was not the cause of my signalr issues. — MrBliz, Sep 26 '15 at 13:31

score 7 · Answer 1 · edited May 23 '17 at 12:06

What you are seeing is a log entry create by: ReflectedHubDescriptorProvider

102 try 
103             { 
104                 return a.GetTypes(); 
105             } 
106             catch (ReflectionTypeLoadException ex) 
107             { 
108                 _trace.TraceWarning("Some of the classes from assembly \"{0}\" could Not be loaded when searching for Hubs. [{1}]\r\n" + 
109                                     "Original exception type: {2}\r\n" + 
110                                     "Original exception message: {3}\r\n", 
111                                     a.FullName, 
112                                     a.Location, 
113                                     ex.GetType().Name, 
114                                     ex.Message); 


116                 return ex.Types.Where(t => t != null); 
117             }

The exception can be caused by a missing dependency in one of the loaded assemblies, the signalr code is iterating all your assemblies. So the cause can be in any of currently loaded assembles. Interesting :get-all-types-in-an-assembly and how-to-prevent-reflectiontypeloadexception-when-calling-assembly-gettypes explains the try catch construction used in the ReflectedHubDescriptorProvider. It is just ignoring the classes/hubs it can't load from the Microsoft.AspNet.SignalR.Owin assembly.

The ReflectionTypeLoadException contains a LoaderExceptions, to access it you can download the source code and add tracing on the ex.LoaderExceptions or add a breakpoint in the sourcecode.

Shouldn't `LoaderExceptions` be included in the Trace itself? I think we can raise this as a bug? — vendettamit, Sep 24 '15 at 15:34
It would give you some information, however I guess it is ignored because ReflectionTypeLoadException will be thrown in many projects without causing any trouble, the problem class is not used or is not a hub. That is why the exception is only a trace and not rethrown to a higher level. — Peter, Sep 24 '15 at 15:42
yes, you are right. But there's no harm getting little more info in trace about the exception. — vendettamit, Sep 24 '15 at 15:43
@peer, yes i'm thinking that this might not even be the cause of the SIgnalR problems i've got, but obviously need to eliminate that possibility. Will download the source tonight and see what i get out of it. — MrBliz, Sep 24 '15 at 16:26
Created a new project, and no longer get the error, but it seems this problem was not the cause of my signalr issues. — MrBliz, Sep 26 '15 at 13:31

score 5 · Answer 2 · answered Sep 26 '15 at 13:30

5

I 'fixed' this problem by creating a new project and copying everything over to the new one/ reinstalling packages again.

I no longer get this error, but my Signalr problems have not gone away, so it looks like this one was a red herring.

answered Sep 26 '15 at 13:30

MrBliz

5,830
15
57
81

score 4 · Answer 3 · answered Sep 28 '15 at 20:38

Glad to hear that you managed to fix assembly loading issue. Here are some tips that might help you get it running!

Enable logging

To troubleshoot SignalR problems the best thing to do is to enable server & client side logging.

Client side:

$.connection.hub.logging = true;
$.connection.hub.start();

Server side:

var hubConnection = new HubConnection("http://www.contoso.com/");
hubConnection.TraceLevel = TraceLevels.All;
hubConnection.TraceWriter = Console.Out;
IHubProxy stockTickerHubProxy = hubConnection.CreateHubProxy("StockTickerHub");
stockTickerHubProxy.On<Stock>("UpdateStockPrice", stock => Console.WriteLine("Stock update for {0} new price {1}", stock.Symbol, stock.Price));
await hubConnection.Start();

Here are full instructions:

http://www.asp.net/signalr/overview/testing-and-debugging/enabling-signalr-tracing

Check your code and troubleshoot the problem

Here is a list of common mistakes you should check:

Misspelled method, incorrect method signature, or incorrect hub name;
Duplicate method name on client;
Mixing Hub and PersistentConnection syntax;
Connection started before subscriptions are added;
Missing method name on the hub proxy;
Hub or hub methods not declared as Public;
Manually serializing data;
Connection limit reached;
Cross-domain connection not set up properly;

Here is a full article on how to troubleshoot SignalR issues with code samples: http://www.asp.net/signalr/overview/testing-and-debugging/troubleshooting

Thanks for the tips. There's a lot there to go through and this is not something i can do on Work time, so it looks like the bounty will expire before i get a chance to go through all of this. :( — MrBliz, Sep 29 '15 at 08:17
I've put server side logging in (I already had client side logging on), and the only file that gets created is the transport one. I would have thought that if the server had found a client to broadcast to then it would have created a SignalR-Init log as well? — MrBliz, Sep 29 '15 at 19:21
Are you sure that your hub is discovered? Is it public? Could you please post some code on how you init SignalR and define hub? — Kaspars Ozols, Sep 30 '15 at 07:08
I fixed it. Turned out to be ordering of autofac method calls in startup.cs will post an updated solution later — MrBliz, Sep 30 '15 at 07:38

score 2 · Answer 4 · answered Sep 28 '15 at 11:59

2

you have to upgrade my Microsoft.Owin.Security package to 2.1.0 with this command

Install-Package Microsoft.Owin.Security -Version 2.1.0

And modify the bindings in my App.config like this

< assemblyIdentity name="Microsoft.Owin.Security" publicKeyToken="31bf3856ad364e35" culture="neutral" / >

< bindingRedirect oldVersion="0.0.0.0-2.1.0.0" newVersion="2.1.0.0" / >

answered Sep 28 '15 at 11:59

Manraj

496
2
15

Microsoft.Owin.Security is at version 3.0.1, which i have. – MrBliz Sep 28 '15 at 12:27
modify the bindings in my App.config and also the new version – Manraj Sep 29 '15 at 08:14

Signalr assembly loading issue OWIN

4 Answers4

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