I have some existing functionality in unmanaged C++ which I wanted to use in a Web App. This code was already wrapped in C++/CLI and used via desktop C# apps. So there is already an existing mixed mode .NET assembly containing the functionality I want to use in a Web App. I also already have Azure hosted web apps that are composed of assemblies containing only C# and I can publish them from Visual Studio 2017 to an Azure App service with no problem.
So I tried to add the mixed mode assembly and started getting errors from the publish about the dependencies of the mixed mode assembly. The only dependency of the mixed mode assembly is on the VC++ runtime so I assumed that was the problem. To prove this I created an Azure VM started IIS on it and published to that and got exactly the same error. I then installed the VS 2017 C++ runtimes on the VM and published again. The error went away and the Web site works fine.
I them logged onto the machine hosting the Web service using Kudu and it appears to have the VS 2017 C++ run time already installed. So I am baffled why I get the error when I publish to it. I have tried adding the runtime DLL's like vcruntime140.dll to my publish but this didn't fix things. I also tried re-installing the runtimes with no luck.
So does anyone have any insights as to why I am getting DLL dependency errors and what I can do to fix it. Ideally I was hoping for a Hello World example of using C++/CLI in a Web App from Microsoft but have not been able to find one.
Note there is a similar question here multi-file c++/cli .net assembly in ASP.NET web site without an answer.