Could not load file or assembly 'System.ServiceModel.Primitives, Version=4.2.0.0

[ssashok10]

I am using Azure Function (C#) which is calling a .NET standard library to call an external WCF service and I am getting the below error. This file is located on the bin folder of my function and the version also correct.

Could not load file or assembly 'System.ServiceModel.Primitives, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

Here are the platform information,
Microsoft.NET.Sdk.Functions (1.0.13)
.NET Standard Library 2.0
System.ServiceModel.Duplex 4.4.2
System.ServiceModel.Http 4.4.2
System.ServiceModel.NetTcp 4.4.2
System.ServiceModel.Security 4.4.2

[zhenlan]

Hi @ssashok10, just to help understand, what's the difference of this Azure Function app than the one you had in #2824?

[ssashok10]

The issue #2824 is different than this issue. The DLL is not copied into the "bin" folder on the issue #2824. Here we are seeing the DLL "System.ServiceModel.Primities" into the bin folder and version also matching. However, the function run time is not able to load it for some reason.

[zhenlan]

@ssashok10, I understand what you described. I am trying to see what caused this result, so that's why my question about what's the difference between the two projects (the project in this issue and the project in #2824). The difference between the two projects may help us to tell why the issue happens to one project but not the other.

[ssashok10]

@zhenlan It's the same project. We initially had an issue with "System.private.servicemodel.dll" which doesn't exist on the bin folder. We overcome this issue with your work around and we ended up facing the current issue. We are able to see the DLL "system.servicemodel.primitives.dll" into the BIN folder with the right version.

[zhenlan]

I see. Looks like somehow the project was trying to use an older version of S.SM.Primitives package. Does it help if you add package reference of System.ServiceModel.Primitives 4.4.2 explicitly to your project?

[ssashok10]

we tried to add it explicitly and it's not helping at all as the DLL already exists in the bin folder. However, we are able to solve this issue something similar in the below article during runtime.

http://putridparrot.com/blog/dynamically-resolve-assemblies-at-runtime/

[zhenlan]

I didn't have this issue last time when I tried .NET Core Azure Functions. At this point, it probably will be helpful if you can share a repro for further investigation.

The blog post is about full framework, so I assume you worked around the issue by implementing assembly resolver using .NET Core APIs?

[ssashok10]

yes...we fixed this issue with assembly resolver.

[Lxiamail]

@ssashok10 Looks like the fix in Azure function may have fixed your problem. Have you tried it?