ASP.net应用程序崩溃 - 无法加载文件或程序集'Microsoft.Threading.Tasks.Extensions.Desktop'

Question

I want to build a Google BigQuery C# ASP.net application using OAuth2 and the .Net 4.5 framework. I ran these NuGet installs

Install-Package Google.Apis.Bigquery.v2 -Pre
Install-Package Google.Apis.Authentication.OAuth2 -Version 1.2.4696.27634

Install-Package Google.Apis -Pre
Install-Package Google.Apis.Auth -Pre

and I placed the relevant "usings" in code-behind file "default.aspx.cs":

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using Google.Apis.Bigquery.v2;
using Google.Apis.Bigquery.v2.Data;

namespace BigQueryDemoApp
{
    public partial class _Default : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            UserCredential credential;
            FileStream stream;

            using (stream = new FileStream(
                    Server.MapPath("~/client_secrets.json"),
                    FileMode.Open, FileAccess.Read)
                )
            {
                GoogleWebAuthorizationBroker.Folder =
                    "Tasks.Auth.Store";
                credential = GoogleWebAuthorizationBroker.
                    AuthorizeAsync(
                    GoogleClientSecrets.Load(stream).Secrets,
                    new[] { BigqueryService.Scope.Bigquery },
                    "user", CancellationToken.None).Result;
            }

            // Initialize the service.
            var Service = new BigqueryService(
                new BaseClientService.Initializer()
                {
                    HttpClientInitializer = credential,
                    ApplicationName = "BigQueryDemo"
                }
            );
        }
    }
}

I set this specific page as the project start page. I picked "Installed application" when I built the Client ID file at the Google console

APIS & auth -> Credentials -> CREATE NEW CLIENT ID

and I made sure I added this file (client_secrets.json) with the solution explorer in VS2013. In the code-behind, I made sure that I correctly mapped to the client_secrets file with Server.MapPath. For the credential machinery, I used this code

<https://code.google.com/p/google-api-dotnet-client/wiki/OAuth2>

as the starting point. When I run the app, it returns a browser error page that starts with

Could not load file or assembly 'Microsoft.Threading.Tasks.Extensions.Desktop, Version=1.0.16.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

and crashes at the "credential =" line. I tried to add in some images of the actual ASP.net crashed browser page showing the Assembly Load Trace / Stack Trace / etc. but it looks like I don't have the account rights for this. When I set a breakpoint at the "credential =" line and then run the app through

DEBUG -> Start Debugging

in VS2013, the page stops at the "credential =" line and a file picker opens, looking for file

"GoogleClientSecrets.cs"

from directory

"c:\\code\\google.com\\google-api-dotnet-client\\default\\Tools\\Google.Apis.Release\\bin\\Debug\\output\\default\\Src\\GoogleApis.Auth\\OAuth2\\GoogleClientSecrets.cs"

which is nowhere on the drive. Using the Assembly Load Trace in the generated ASP.net error page, I tried digging around through the suggested configuration files but nothing worked. More generally, I tried looking for this issue in StackOverflow and while I did find some mention of it, none of that material helped.

Answer 1

Because the error is based on the fact that the latest version of Microsoft.Bcl.Async doesn't work in .NET 4.5, you can try to do the following:

Open your Package Manager Console, and run the following commands:
1) Uninstall-Package Microsoft.Bcl.Async -Force
2) Install-Package Microsoft.Bcl.Async -Version

It works in a sample I'm currently writing. Please let me know if it works for you.

UPDATE (March 21st): You can update the package (new version 1.0.166-beta is available - https://www.nuget.org/packages/Microsoft.Bcl.Async/1.0.166-beta ).
I tested it on VS2013 with .NET 4.5 framework and it works.

Answer 2

They released a new version of -Package Microsoft.Bcl.Async.

If somebody has this issue, please install the "latest" version instead of 1.0.16.

I hope it works for you.

Answer 3

I already encountered this error before. It looks like the Bcl.Async package contains a reference to Microsoft.Threading.Tasks.Extensions.Desktop when you run a .NET 4.0 applications but somehow it is missing in .NET 4.5 application.

My advice for you (until I'll figure our with the owner of Microsoft.Bcl.Async why it happens) is to copy Microsoft.Threading.Tasks.Extensions.Desktop from packages\\Microsoft.Bcl.Async.1.0.165\\lib\\net40\\Microsoft.Threading.Tasks.Extensions.Desktop.dll to your BIN folder. It should solve this issue.

UPDATE (March 17th): Consider adding the following Post-build event to your project:

copy /Y "$(SolutionDir)packages\\Microsoft.Bcl.Async.1.0.16\\lib\\net40\\Microsoft.Threading.Tasks.Extensions.Desktop.dll" "$(TargetDir)Microsoft.Threading.Tasks.Extensions.Desktop.dll"

Unfortunately, there isn't a solution for this problem yet from the owners of the Bcl.Async package.

Answer 4

This approach did not fix the issue - I got the same runtime error. But after a rebuild, I noticed that the VS2013 compiler showed this warning, which I formatted a little for the SO editor

C:\Program Files (x86)\MSBuild\12.0\bin\Microsoft.Common.CurrentVersion.targets(1635,5): warning
MSB3247: Found conflicts between different versions of the same dependent assembly. In Visual 
Studio, double-click this warning (or select it and press Enter) to fix the conflicts; 
otherwise, add the following binding redirects to the "runtime" node in the application 
configuration file:

<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
        <assemblyIdentity name="Microsoft.Threading.Tasks.Extensions.Desktop" culture="neutral" publicKeyToken="b03f5f7f11d50a3a" />
        <bindingRedirect oldVersion="0.0.0.0-1.0.165.0" newVersion="1.0.165.0" />
    </dependentAssembly>
</assemblyBinding>

so I dropped the suggested block in the app web.config file. Then the app decided to work. I have no idea why it works now, but I get the impression that the XML block and / or the reference fix you mentioned somehow touched the Microsoft.Threading.Tasks.Extensions.Desktop DLL, or some low-level machinery inside .Net, or both. Or neither, for all I know. Anyway, thanks for your help. I only wish I had a better understanding of the internal machinery.