Last logging parameter of Azure Function (ILogger or TraceWriter) not accepted

Question

After upgrading my own project from an earlier (a few months back) version of Azure Functions to current, I get the following error upon launching from VS.

GetLoginUrl: Microsoft.Azure.WebJobs.Host: Error indexing method 'Login.GetLoginUrl'. Microsoft.Azure.WebJobs.Host: Cannot bind parameter 'log' to type ILogger. Make sure the parameter Type is supported by the binding. If you're using binding extensions (e.g. ServiceBus, Timers, etc.) make sure you've called the registration method for the extension(s) in your startup code (e.g. config.UseServiceBus(), config.UseTimers(), etc.).

Before, I used to have TraceWriter log as the last parameter to my methods but then I found out I should be using ILogger instead. Before I made the change, I was getting the same error as above.

The ILogger seems to be mapped to assembly Microsoft.Extensions.Logging.Abstractions. Perhaps this is why it is not recognized? Which ILogger should be used? Here is the method signature.

[FunctionName("GetLoginUrl")]
public static HttpResponseMessage GetLoginUrl(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = null)]HttpRequestMessage req,
    ILogger log)

I did not try to deploy this to Azure.

Unfortunately, creating a brand new Functions project does not help as there are no .CS files to look up to in order to correct this.

Your code looks exactly like my working code that uses ILogger with Azure Functions. Does the problem go away if you delete all referenced NuGet packages except for Microsoft.NET.Sdk.Functions then add the specific ones you need back? — Scott Chamberlain
Yes, exactly! That does it. Please see my other comment for details. Briefly, all "Microsoft.Azure.WebJobs.*" assemblies were redundant. — wpfwannabe

Mikhail Shilkov Mikhail Shilkov · Accepted Answer · 2017-09-28T14:07:35

Microsoft.Extensions.Logging.Abstractions is the correct assembly.

You are probably referencing some older NuGet packages directly (e.g. Microsoft.Azure.WebJobs). If so, be sure to remove it. Unless you are using some additional binding, your csproj references should look as simple as this:

<ItemGroup>           
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="1.0.4" />
</ItemGroup>

Last logging parameter of Azure Function (ILogger or TraceWriter) not accepted

1 Answers