System.Net.Http - Could not load file or assembly, then Cannot load a reference assembly for execution

Question

When I publish a csproj I get the message:

Could not load file or assembly System.Net.Http

If I add it to the project and republish, I get the message:

[BadImageFormatException: Cannot load a reference assembly for execution.] [BadImageFormatException: Could not load file or assembly 'System.Net.Http'

So it's like catch-22

This is the system.web of my web.config

  <system.web>
    <customErrors mode="Off" />
    <compilation debug="true" targetFramework="4.7.2" />
    <httpRuntime targetFramework="4.6" />
  </system.web>

If present try delete the "System.Net.Http.dll" (or the dll that need that namespace) from bin\Release folder, after that it should work. — Legion
– Legion, Commented Aug 8, 2018 at 13:07
Is this on your local machine or on the published environment? Is this .NET Core? What version of .NET? — Victor Procure
– Victor Procure, Commented Aug 8, 2018 at 13:08
Mh... i was thinking about my environment, but the dll should be in the publish environment too, maybe not in the same folder. — Legion
– Legion, Commented Aug 8, 2018 at 13:10
Remove the file from the project. It looks like the file was added to the project. I would open the .proj file with Notepad and see where the Http is found. — jdweng
– jdweng, Commented Aug 8, 2018 at 13:14
Thanks for the replies; this is happening on the published environment; I've added to my original post my web.config's system.web — robertocg72
– robertocg72, Commented Aug 8, 2018 at 13:16

Victor Procure · Accepted Answer · 2018-08-08 13:16:59Z

7

First things first:

Make sure all your projects are pointing at the same version of System.Net.Http, you can manually verify this by checking your bin folder after a compile. Just make sure the DLLs are the same version.

Then Make sure all your App.Config/Web.Config have a binding redirect

<dependentAssembly>
    <assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-4.2.0.0" newVersion="4.0.0.0" />
</dependentAssembly>

Lastly make sure you are not accidently publishing a 32-bit DLL with an 64-bit executable. This will also cause the BadImageFormatException.

Check your project settings to make sure you are targetting the right environment, then check your dependencies to make sure they are not accidently pulling/publishing the wrong DLL.

answered Aug 8, 2018 at 13:16

Victor Procure

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1 Comment

Paradox Over a year ago

Can you please elaborate on "Lastly make sure you are not accidently publishing a 32-bit DLL with an 64-bit executable. This will also cause the BadImageFormatException"?

WantToDo · Accepted Answer · 2020-03-03 14:35:07Z

2

I solved it by install .Net framework 4.7.2 from https://support.microsoft.com/en-us/help/4054531/microsoft-net-framework-4-7-2-web-installer-for-windows

answered Mar 3, 2020 at 14:35

WantToDo

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