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> 

Answer 1

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.