Could not load file or assembly 'System.Net.Http'

Question

1. Error when starting app

Could not load file or assembly 'System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

Stack Trace: 


[FileNotFoundException: Could not load file or assembly 'System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.]
   System.Web.Http.GlobalConfiguration..cctor() +0

[TypeInitializationException: The type initializer for 'System.Web.Http.GlobalConfiguration' threw an exception.]
   System.Web.Http.GlobalConfiguration.get_Configuration() +14
   SerilogWeb.Classic.WebApi.PreApplicationStartModule.Register() +10

[InvalidOperationException: The pre-application start initialization method Register on type SerilogWeb.Classic.WebApi.PreApplicationStartModule threw an exception with the following error message: The type initializer for 'System.Web.Http.GlobalConfiguration' threw an exception..]
   System.Web.Compilation.BuildManager.InvokePreStartInitMethodsCore(ICollection`1 methods, Func`1 setHostingEnvironmentCultures) +614
   System.Web.Compilation.BuildManager.InvokePreStartInitMethods(ICollection`1 methods) +138
   System.Web.Compilation.BuildManager.CallPreStartInitMethods(String preStartInitListPath, Boolean& isRefAssemblyLoaded) +164
   System.Web.Compilation.BuildManager.ExecutePreAppStart() +156
   System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters, PolicyLevel policyLevel, Exception appDomainCreationException) +695

[HttpException (0x80004005): The pre-application start initialization method Register on type SerilogWeb.Classic.WebApi.PreApplicationStartModule threw an exception with the following error message: The type initializer for 'System.Web.Http.GlobalConfiguration' threw an exception..]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +658
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +89
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +190

2. Csproj

...
  <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
...
  <Reference Include="System.Net.Http" />
...

When I display System.Net.Http properties in solution it has:

Aliases = global
CopyLocal = False
Path = C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\System.Net.Http.dll
Resolved = True
Runtime Version = v4.0.30319
Specific Version = True
Strong Name = True
Version = 4.0.0.0

3. Fusionlog

When starting this app, there are two logs, for v4.0.0.0 and v.4.1.1.1. Is this an issue?

For v4.0.0.0

*** Assembly Binder Log Entry  (x) ***

The operation failed.
Bind result: hr = 0x80070002. The system cannot find the file specified.

Assembly manager loaded from:  C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll
Running under executable  C:\Program Files (x86)\IIS Express\iisexpress.exe
--- A detailed error log follows. 

=== Pre-bind state information ===
LOG: DisplayName = System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
 (Fully-specified)
LOG: Appbase = x
LOG: Initial PrivatePath = x\bin
LOG: Dynamic Base = C:\Users\y\AppData\Local\Temp\Temporary ASP.NET Files\vs\xyz
LOG: Cache Base = C:\Users\y\AppData\Local\Temp\Temporary ASP.NET Files\vs\xyz
LOG: AppName = 12345
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: x\web.config
LOG: Using host configuration file: w\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: GAC Lookup was unsuccessful.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http/System.Net.Http.EXE.
LOG: All probing URLs attempted and failed.

For v4.1.1.0

*** Assembly Binder Log Entry  (x) ***

The operation failed.
Bind result: hr = 0x80070002. The system cannot find the file specified.

Assembly manager loaded from:  C:\Windows\Microsoft.NET\Framework\v4.0.30319\clr.dll
Running under executable  C:\Program Files (x86)\IIS Express\iisexpress.exe
--- A detailed error log follows. 

=== Pre-bind state information ===
LOG: DisplayName = System.Net.Http, Version=4.1.1.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL
 (Fully-specified)
LOG: Appbase = file:///C:/x/
LOG: Initial PrivatePath = C:\x\bin
LOG: Dynamic Base = C:\Users\y\AppData\Local\Temp\Temporary ASP.NET Files\vs\xyz
LOG: Cache Base = C:\Users\y\AppData\Local\Temp\Temporary ASP.NET Files\vs\xyz
LOG: AppName = 12345
Calling assembly : (Unknown).
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\x\web.config
LOG: Using host configuration file: w\Documents\IISExpress\config\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Redirect found in application configuration file: 4.1.1.1 redirected to 4.1.1.1.
LOG: ProcessorArchitecture is locked to MSIL.
LOG: Post-policy reference: System.Net.Http, Version=4.1.1.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL
LOG: GAC Lookup was unsuccessful.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http/System.Net.Http.DLL.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/Users/y/AppData/Local/Temp/Temporary ASP.NET Files/vs/xyz/12345/System.Net.Http/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http.EXE.
LOG: Attempting download of new URL file:///C:/x/bin/System.Net.Http/System.Net.Http.EXE.
LOG: All probing URLs attempted and failed.

4. GAC

$ gacutil -l

...
System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL
...

Is System.Net.Http.dll in C:\Windows\Microsoft.NET\assembly... ?

• GAC_32 - no
• GAC_64 - no
• GAC_MSIL - yes

5. This is assembly first location

C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Net.Http\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Net.Http.dll

System.Net.Http.dll 197 kB (file version: 4.7.2046.0)

Assembly check:

$ sn.exe -T "C:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Net.Http\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Net.Http.dll"

Microsoft (R) .NET Framework Strong Name Utility  Version 4.0.30319.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key token is b03f5f7f11d50a3a

6. This is assembly second location

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.6.1\System.Net.Http.dll

System.Net.Http.dll 84 kB (file version: 4.6.1055.0)

Assembly check:

$ sn.exe -T "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\System.Net.Http.dll"

Microsoft (R) .NET Framework Strong Name Utility  Version 4.0.30319.0
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key token is b03f5f7f11d50a3a

I think I have all information, but I can't figure out the solution. I might replace .NETFramework assembly with that from GAC or the way around, but it is blind shot - I don't know what is the reason.

// UPDATE

Web.config

<?xml version="1.0" encoding="utf-8"?>
<configuration>

  <system.web>
    <compilation debug="true" targetFramework="4.6.1" />
    <httpRuntime targetFramework="4.6.1" />
  </system.web>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
...
      <dependentAssembly>
        <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.1.1.1" newVersion="4.1.1.1" />
      </dependentAssembly>
...
    </assemblyBinding>
  </runtime>


</configuration>

Solution

Thanks to @Jehof:

Reason

Web.config had redirect of System.Net.Http from 4.0.0 to 4.1.1, and GAC had only assembly version 4.0.0.

<?xml version="1.0" encoding="utf-8"?>
<configuration>

  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
...
      <dependentAssembly>
        <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.1.1.1" newVersion="4.1.1.1" />
      </dependentAssembly>
...
    </assemblyBinding>
  </runtime>


</configuration>

Solution

Removing this redirect solved the problem.

Root cause

I think, I had this assembly redirect in Web.config, because I installed System.Net.Http via nuget at some point, and then uninstalled it. However assembly redirect was not removed automatically.

Comments

[Jehof]

why do you have an assembly version redirect in your app.config?

[one_mile_run]

wow, good point. I have not notice this, please see my update in question. I have no idea why it is there, for sure some nuget package added this.

[Jehof]

Do you get the error when running this locally on your development machine or on a production/test server?

[one_mile_run]

@Jehof: Perfect! Following your trail, I removed dependentAssembly redirect for System.Net.Http both in Web.config and in my test project in app.config. And it works! Feel free to write an answer, I will mark it as the solution.

[laika]

@one_mile_run Check this answer regarding assembly redirects. Furthermore it would be good if you check which package has caused this dependency. BTW, System.Net.Http assemblies of version 4.1 and higher are no longer located in GAC, they are distributed out-of-band.

[one_mile_run]

@laika: Very useful information. Is there any dependency checker/viewer for nuget packages?

[one_mile_run]

@Jehof: I think, I had this assembly redirect in Web.config, because for this project I installed System.Net.Http via nuget at some point, and then uninstalled it. However assembly redirect was not removed automatically.