Getting Method not found error when accessing to Azure KeyVault - azure-keyvault

Question

I am trying to get my connection string from Azure Keyvault in the application_start event of my .Net web application.
protected void Application_Start(Object sender, EventArgs e)
{
var azureServiceTokenProvider = new AzureServiceTokenProvider();
var kvClient = new KeyVaultClient(new KeyVaultClient.AuthenticationCallback(GetToken));
RegisterRoutes(RouteTable.Routes);
}
public static async Task<string> GetToken(string authority, string resource, string scope)
{
var authContext = new AuthenticationContext(authority);
ClientCredential clientCred = new ClientCredential(ConfigurationManager.AppSettings["clientId"],
ConfigurationManager.AppSettings["clientSecret"]);
AuthenticationResult result = await authContext.AcquireTokenAsync(resource, clientCred);
if (result == null)
throw new InvalidOperationException("Failed to obtain the JWT token");
return result.AccessToken;
}
But I get this error below.
This is a new MVC web application with .Net 4.6.
The exact same code works fine on a Console app.
I compared the package versions and they are the same.
I also tried to put that code in the constructor of a controller but the same error.
Any ideas?
Method not found: 'Void
Microsoft.Azure.KeyVault.KeyVaultClient..ctor(AuthenticationCallback,
System.Net.Http.DelegatingHandler[])'.
[MissingMethodException: Method not found: 'Void
Microsoft.Azure.KeyVault.KeyVaultClient..ctor(AuthenticationCallback,
System.Net.Http.DelegatingHandler[])'.]
WebApplication1.MvcApplication.Application_Start() in
C:\Users\test\Documents\Visual Studio
2017\Projects\ConsoleApp1\WebApplication1\Global.asax.cs:27
[HttpException (0x80004005): Method not found: 'Void
Microsoft.Azure.KeyVault.KeyVaultClient..ctor(AuthenticationCallback,
System.Net.Http.DelegatingHandler[])'.]
System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext
context, HttpApplication app) [phone]
System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr
appContext, HttpContext context, MethodInfo[] handlers) +118
System.Web.HttpApplication.InitSpecial(HttpApplicationState state,
MethodInfo[] handlers, IntPtr appContext, HttpContext context) +173
System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr
appContext, HttpContext context) +336
System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr
appContext) +296
[HttpException (0x80004005): Method not found: 'Void
Microsoft.Azure.KeyVault.KeyVaultClient..ctor(AuthenticationCallback,
System.Net.Http.DelegatingHandler[])'.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) [phone]
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +95
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest
wr, HttpContext context) +254
<packages>
<package id="Antlr" version="3.4.1.9004" targetFramework="net461" />
<package id="bootstrap" version="3.0.0" targetFramework="net461" />
<package id="jQuery" version="1.10.2" targetFramework="net461" />
<package id="jQuery.Validation" version="1.11.1" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.Agent.Intercept" version="2.0.6" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.DependencyCollector" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.PerfCounterCollector" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.Web" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.WindowsServer" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel" version="2.2.0" targetFramework="net461" />
<package id="Microsoft.AspNet.Mvc" version="5.2.3" targetFramework="net461" />
<package id="Microsoft.AspNet.Razor" version="3.2.3" targetFramework="net461" />
<package id="Microsoft.AspNet.Web.Optimization" version="1.1.3" targetFramework="net461" />
<package id="Microsoft.AspNet.WebPages" version="3.2.3" targetFramework="net461" />
<package id="Microsoft.Azure.KeyVault" version="2.3.2" targetFramework="net461" />
<package id="Microsoft.Azure.KeyVault.WebKey" version="2.0.7" targetFramework="net461" />
<package id="Microsoft.Azure.Services.AppAuthentication" version="1.1.0-preview" targetFramework="net461" />
<package id="Microsoft.CodeDom.Providers.DotNetCompilerPlatform" version="1.0.7" targetFramework="net461" />
<package id="Microsoft.Extensions.Configuration" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.Configuration.Abstractions" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.Configuration.AzureKeyVault" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.Configuration.FileExtensions" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.FileProviders.Abstractions" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.FileProviders.Physical" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.FileSystemGlobbing" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.Extensions.Primitives" version="2.0.0" targetFramework="net461" />
<package id="Microsoft.IdentityModel.Clients.ActiveDirectory" version="3.14.2" targetFramework="net461" />
<package id="Microsoft.jQuery.Unobtrusive.Validation" version="3.2.3" targetFramework="net461" />
<package id="Microsoft.Net.Compilers" version="2.1.0" targetFramework="net461" developmentDependency="true" />
<package id="Microsoft.Rest.ClientRuntime" version="2.3.8" targetFramework="net461" />
<package id="Microsoft.Rest.ClientRuntime.Azure" version="3.3.7" targetFramework="net461" />
<package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net461" />
<package id="Modernizr" version="2.6.2" targetFramework="net461" />
<package id="Newtonsoft.Json" version="6.0.8" targetFramework="net461" />
<package id="Respond" version="1.2.0" targetFramework="net461" />
<package id="System.Runtime.CompilerServices.Unsafe" version="4.4.0" targetFramework="net461" />
<package id="WebGrease" version="1.5.2" targetFramework="net461" />
</packages>

Answer 1

I had to remove System.Net.Http from references and re-add it since the application was loading 2 different versions of that library for some unknown reason.

Answer 2

In our case, we solved it using the following property in projects depending on KeyVault nuget package:
<ImplicitlyExpandNETStandardFacades>false</ImplicitlyExpandNETStandardFacades>
As a result, this forces a reference to System.Net.Http in GAC.

Answer 3

Faced similar issue. Solution for me was:
I had solution in .NET Framework 4.6.2 and when I added the KeyVault SDK from nugget it also took System.Net.Http 4.3.4 with that. But accordingly to the description of the key vault SDK, it is requirement just for .NET standard 1.4 and 2.0 not for .NET Framework. As my whole application used the System.Net.Http 4.0.0 from GAC, I manually removed the System.Net.Http added via nugget (removed it from packages.config) and added reference from GAC to version 4.0.0.
After that, I got rid of the error.