Unable to debug and publish Azure Function from Visual Studio 2017

Question

I used to debug and publish my Azure Function Project using Visual Studio 2017.

However suddenly everything stopped working.

When i tried to debug the project i got the error "A project with an Output Type of Class Library cannot be started directly.". When i tried to publish the project, the option to publish to Azure disappeared and i'm only offered to publish to a folder. When trying to create a profile i can also only choose the Folder Profile type.

I saw a similar behavior once in a Web Project when the "Project Sdk" Attribute in the .csproj file was wrong but i doublechecked it with a newly created Azure Function Project and it was the same. When i create a new function project, i can publish to Azure as i could before.

I'm using the following packages:

along with .NET Framework 4.7.1.

Also i'm referencing some other projects from my solution containing Business Logic.

I ended up creating a new function project, copying everything there and now it's working again as expected.

Does anybody know how this could happen and how to fix it without creating everything from scratch?

Answer 1

In my case I was able to fix it by ensuring the NuGet package for Azure Functions was referenced:

<PackageReference Include="Microsoft.NET.Sdk.Functions" Version="1.0.14" />    

Answer 2

I just had this same thing happen to me. I added a new Azure Function project to an existing solution, and it wouldn't let me debug it. I added an additional Azure Function project just to test it, and it worked fine. Compared the .csproj files, they were both correct.

I restarted Visual Studio and I was able to debug both Function projects, though I don't know if that will always fix the problem.