BUG: Object reference not set.... .net 6 functions

[svrooij]

Describe the issue
When using this library in a new Azure Functions project (.net6, runtime V4) it works locally but not on Azure.

Object reference not set to an instance of an object.

To Reproduce

1. Create new Azure functions project with .Net 6
2. Add a new project without dependencies and reference it in your functions project
3. Deploy to Azure
4. Call /api/swagger.json

Expected behavior
I expect that swagger would just work like it does locally.

Screenshots

Environment (please complete the following information, if applicable):

• OS: Azure (Windows Service plan, FUNCTIONS_EXTENSION_VERSION = ~4, FUNCTIONS_WORKER_RUNTIME = dotnet)
• Version 1.0.0 (nuget)

[vinhent]

I am having the exact same issue (.net6, runtime V4). It works just fine locally but not on Azure.

[PedroLucasSilva]

I had the same problem and I solved it based on an old issue. Where the person indicated that all projects on their system must have at least one dependency. I added a random package to a project of mine that didn't have any and it started working.

[McNerdius]

Bizarre issue. The "at least one dependency per project" workaround worked for me as well.

[vinhent]

It fixed it for me as well. I had a project that contains only interfaces and didn't have any dependencies.

I added this randomly:

Do you have an idea of a better nuget package to be used in that context?

[svrooij]

I can confirm that this hack fixes my problem, but I think the need for at least one dependency in each project, should be treated as a BUG. Because it really is a strange thing to require.

I just used this package because I was already using the dependency injection anyways.

  <ItemGroup>
    <!-- Hack to fix OpenApi UI and Json in Azure, requiring at least one dependency for each project. -->
    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
  </ItemGroup>

[svrooij]

I had the same problem and I solved it based on an old issue. Where the person indicated that all projects on their system must have at least one dependency. I added a random package to a project of mine that didn't have any and it started working.

@PedroLucasSilva do you maybe have the link to that other issue, seems like we need to reference it here.

[justinyoo]

@svrooij It's a known issue #302

[svrooij]

@justinyoo But why does it work locally?

[justinyoo]

@svrooij I have no idea. I haven't got such an experience at all. I use exactly the same settings (.NET 6, v4, in-proc). Would you please tell me how to reproduce the issue?

[svrooij]

Since the comments above provided a work-around, this is what triggers the error:

1. Create a new azure Functions app with OpenApi support
2. Add an additional project, WITHOUT dependencies.
3. Add the second project as a project dependency to the functions project.
4. The swagger ui should still appear locally, and the endpoint from the template should be in the swagger ui.
5. Publish to Azure and it stops working, with the error above in the ligging.

[justinyoo]

@svrooij Alright. I tried to reproduce on my end, but... my app is still working. Here's my app structure:

https://github.com/fitability/fitability-api/tree/main/users

• Api.Users ➡️ main function app - .NET 6, in-proc, v4
• Api.Models ➡️ class library with no dependency, but added to Api.Users - .NET Standard 2.0
• Api.Users.Models ➡️ class library with no dependency, no added to Api.Users - .NET Standard 2.0

They are buit and deployed to Azure through GitHub Actions, and it's working.

[chris-parker-bliss]

I wanted to make a quick note to say that we've just run into this issue when running locally - in our setup we've got an Azure function project referencing a "shared" net6.0 class library.

Using the hack suggested by @svrooij - adding the Microsoft.Extensions.DependencyInjection.Abstractions dependency to that shared project - has gotten it working again.

[justinyoo]

@svrooij Alright. I tried to reproduce on my end, but... my app is still working. Here's my app structure:

https://github.com/fitability/fitability-api/tree/main/users

• Api.Users ➡️ main function app - .NET 6, in-proc, v4
• Api.Models ➡️ class library with no dependency, but added to Api.Users - .NET Standard 2.0
• Api.Users.Models ➡️ class library with no dependency, no added to Api.Users - .NET Standard 2.0

They are buit and deployed to Azure through GitHub Actions, and it's working.

I changed the Api.Models project targeting to net6.0

https://github.com/fitability/fitability-api/blob/27216269c6b6e684c957abbbbde27e0640b3f947/users/src/Fitability.Api.Models/Fitability.Api.Models.csproj#L3-L6

and updated the package version to v1.3.0.

https://github.com/fitability/fitability-api/blob/27216269c6b6e684c957abbbbde27e0640b3f947/users/src/Fitability.Api.Users/Fitability.Api.Users.csproj#L6-L9

It works OK both locally and Azure on my end.

@svrooij @chris-parker-bliss Would you please try on your end?

[svrooij]

@justinyoo it happens when there are no dependencies in the class library and it is set to .NET6 as target framework.

[justinyoo]

That's exactly what I did. The Api.Models project is a class library targeting net6.0 with no dependency.

[chris-parker-bliss]

Hi @justinyoo - I can confirm that even after updating to v1.3.0 of the Microsoft.Azure.WebJobs.Extensions.OpenApi package I'm still seeing the following error when my function app references a net6.0 class library which has no dependencies:

Object reference not set to an instance of an object.

   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiHttpTriggerContext.<>c.<GetRuntimeFilenameAsync>b__43_1(KeyValuePair`2 target)
   at System.Linq.Utilities.<>c__DisplayClass2_0`3.<CombineSelectors>b__0(TSource x)
   at System.Linq.Enumerable.SelectListIterator`2.MoveNext()
   at System.Linq.Enumerable.SelectManySingleSelectorIterator`2.MoveNext()
   at System.Linq.Enumerable.Contains[TSource](IEnumerable`1 source, TSource value, IEqualityComparer`1 comparer)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiHttpTriggerContext.<>c__DisplayClass43_0.<GetRuntimeFilenameAsync>b__3(<>f__AnonymousType0`3 r)
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Func`2 predicate, Boolean& found)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiHttpTriggerContext.GetRuntimeFilenameAsync(String functionAppDirectory)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiHttpTriggerContext.SetApplicationAssemblyAsync(String functionAppDirectory, Boolean appendBin)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Extensions.OpenApiHttpTriggerContextExtensions.AuthorizeAsync(Task`1 context, IHttpRequestDataObject req)
   at Microsoft.Azure.WebJobs.Extensions.OpenApi.OpenApiTriggerFunctionProvider.RenderSwaggerUI(HttpRequest req, ExecutionContext ctx, ILogger log)