Error converting 1 input parameters for Function: Cannot convert input parameter 'token' to type 'System.Threading.CancellationToken'

[ThomasArdal]

I've implemented an Azure Function based on the Isolated model. The function processes message from a topic subscription on Azure Service Bus. The definition on the Run method looks similar to this:

[Function("MyFunction")]
public async Task Run(
    [ServiceBusTrigger("topic", "subscription", Connection = "connectionString")]string mySbMsg,
    CancellationToken token)

The function is running and processing messages. But I see errors like this logged from time to time:

Microsoft.Azure.Functions.Worker.FunctionInputConverterException: Error converting 1 input parameters for Function 'MyFunction': Cannot convert input parameter 'token' to type 'System.Threading.CancellationToken' from type 'System.String'. Error:System.Text.Json.JsonException: 'p' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 0.
 ---> System.Text.Json.JsonReaderException: 'p' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.
   at System.Text.Json.ThrowHelper.ThrowJsonReaderException(Utf8JsonReader& json, ExceptionResource resource, Byte nextByte, ReadOnlySpan`1 bytes)
   at System.Text.Json.Utf8JsonReader.ConsumeValue(Byte marker)
   at System.Text.Json.Utf8JsonReader.ReadFirstToken(Byte first)
   at System.Text.Json.Utf8JsonReader.ReadSingleSegment()
   at System.Text.Json.Utf8JsonReader.Read()
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, JsonReaderException ex)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.ContinueDeserialize(ReadBufferState& bufferState, JsonReaderState& jsonReaderState, ReadStack& readStack)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.DeserializeAsync(Stream utf8Json, CancellationToken cancellationToken)
   at System.Text.Json.Serialization.Metadata.JsonTypeInfo`1.DeserializeAsObjectAsync(Stream utf8Json, CancellationToken cancellationToken)
   at Microsoft.Azure.Functions.Worker.Converters.JsonPocoConverter.GetConversionResultFromDeserialization(Byte[] bytes, Type type) in D:\a\_work\1\s\src\DotNetWorker.Core\Converters\JsonPocoConverter.cs:line 66
   at Microsoft.Azure.Functions.Worker.Context.Features.DefaultFunctionInputBindingFeature.BindFunctionInputAsync(FunctionContext context) in D:\a\_work\1\s\src\DotNetWorker.Core\Context\Features\DefaultFunctionInputBindingFeature.cs:line 94
   at MyFunction.DirectFunctionExecutor.ExecuteAsync(FunctionContext context) in D:\a\1\s\src\MyFunction\Microsoft.Azure.Functions.Worker.Sdk.Generators\Microsoft.Azure.Functions.Worker.Sdk.Generators.FunctionExecutorGenerator\GeneratedFunctionExecutor.g.cs:line 32
   at Microsoft.Azure.Functions.Worker.OutputBindings.OutputBindingsMiddleware.Invoke(FunctionContext context, FunctionExecutionDelegate next) in D:\a\_work\1\s\src\DotNetWorker.Core\OutputBindings\OutputBindingsMiddleware.cs:line 13

The error seems to happen in some generated source code:

/// <inheritdoc/>
public async ValueTask ExecuteAsync(FunctionContext context)
{
    var inputBindingFeature = context.Features.Get<IFunctionInputBindingFeature>();
    // ⬇️ The error happens when calling BindFunctionInputAsync
    var inputBindingResult = await inputBindingFeature.BindFunctionInputAsync(context);
    var inputArguments = inputBindingResult.Values;

I don't understand why the generated code is trying to parse the CancelationToken as JSON. I already have the JSON sent over the service bus as the first parameter.

Any help would be appreciated.

(copy from: https://stackoverflow.com/questions/77898023/error-converting-1-input-parameters-for-function-cannot-convert-input-parameter)

[kshyju]

What version of nuget packages are you using?

For your code, I got the below code generated. Is that not what you are seeing? Can you share the full code in the ExecuteAsync from the generated type?

public async ValueTask ExecuteAsync(FunctionContext context)
{
    var inputBindingFeature = context.Features.Get<IFunctionInputBindingFeature>();
    var inputBindingResult = await inputBindingFeature.BindFunctionInputAsync(context);
    var inputArguments = inputBindingResult.Values;

    if (string.Equals(context.FunctionDefinition.EntryPoint, "GH2245ServiceBusTrigger.Function1.Run", StringComparison.Ordinal))
    {
        var instanceType = types["GH2245ServiceBusTrigger.Function1"];
        var i = _functionActivator.CreateInstance(instanceType, context) as global::GH2245ServiceBusTrigger.Function1;
        await i.Run((string)inputArguments[0], (global::System.Threading.CancellationToken)inputArguments[1]);
    }
}

Below are the relevant nuget package versions I used when I tried to repro

<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.21.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.ServiceBus" Version="5.16.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.16.4" />         

[ThomasArdal]

I don't have all of the lines from the ExecuteAsync method but here is what I have:

public async ValueTask ExecuteAsync(FunctionContext context)
{
    var inputBindingFeature = context.Features.Get<IFunctionInputBindingFeature>();
    var inputBindingResult = await inputBindingFeature.BindFunctionInputAsync(context);
    var inputArguments = inputBindingResult.Values;
 
    if (string.Equals(context.FunctionDefinition.EntryPoint, "MyFunction.Function1.Run", StringComparison.Ordinal))
    {
        var instanceType = types["MyFunction.Function1"];
        var i = _functionActivator.CreateInstance(instanceType, context) as global::MyFunction.Function1;
        i.Run((global::Microsoft.Azure.Functions.Worker.TimerInfo)inputArguments[0]);
    }
    else if (string.Equals(context.FunctionDefinition.EntryPoint, "MyFunction.Function2.Run", StringComparison.Ordinal))
    {

I replaced the function namespace and names in the code. As you can see, there are two functions in the function app. One being the service bus triggered one and the other being a timered function. The issue is with the service bus triggered function.

Here are the NuGet packages I'm using:

<PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.20.1" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.ServiceBus" Version="5.15.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Extensions.Timer" Version="4.3.0" />
<PackageReference Include="Microsoft.Azure.Functions.Worker.Sdk" Version="1.16.4" />

The project is running on .NET 8.

[kshyju]

I don't have all of the lines from the ExecuteAsync method

This code is source generated. You can find it under "Microsoft.Azure.Functions.Worker.Sdk.Generators" -> Microsoft.Azure.Functions.Worker.Sdk.Generators.FunctionExecutionGenerator -> GeneratedFunctionExecutor.g.cs

[ThomasArdal]

But I think that the code looks exactly like yours, with the only difference that there's an else if in it because of two functions instead of one. The error is thrown when calling this method:

var inputBindingResult = await inputBindingFeature.BindFunctionInputAsync(context);

[ThomasArdal]

Here's the full source code generated locally:

// <auto-generated/>
using System;
using System.Threading.Tasks;
using System.Collections.Generic;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Context.Features;
using Microsoft.Azure.Functions.Worker.Invocation;
namespace MyFunction
{
    [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
    internal class DirectFunctionExecutor : IFunctionExecutor
    {
        private readonly IFunctionActivator _functionActivator;
        private readonly Dictionary<string, Type> types = new Dictionary<string, Type>()
        {
            { "MyFunction.Heartbeat", Type.GetType("MyFunction.Heartbeat, MyFunction, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null") },
            { "MyFunction.HttpRequest", Type.GetType("MyFunction.HttpRequest, MyFunction, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null") }
        };

        public DirectFunctionExecutor(IFunctionActivator functionActivator)
        {
            _functionActivator = functionActivator ?? throw new ArgumentNullException(nameof(functionActivator));
        }

        /// <inheritdoc/>
        public async ValueTask ExecuteAsync(FunctionContext context)
        {
            var inputBindingFeature = context.Features.Get<IFunctionInputBindingFeature>();
            var inputBindingResult = await inputBindingFeature.BindFunctionInputAsync(context);
            var inputArguments = inputBindingResult.Values;

            if (string.Equals(context.FunctionDefinition.EntryPoint, "MyFunction.Heartbeat.Run", StringComparison.Ordinal))
            {
                var instanceType = types["MyFunction.Heartbeat"];
                var i = _functionActivator.CreateInstance(instanceType, context) as global::MyFunction.Heartbeat;
                i.Run((global::Microsoft.Azure.Functions.Worker.TimerInfo)inputArguments[0]);
            }
            else if (string.Equals(context.FunctionDefinition.EntryPoint, "MyFunction.HttpRequest.Run", StringComparison.Ordinal))
            {
                var instanceType = types["MyFunction.HttpRequest"];
                var i = _functionActivator.CreateInstance(instanceType, context) as global::MyFunction.HttpRequest;
                await i.Run((string)inputArguments[0], (global::System.Threading.CancellationToken)inputArguments[1]);
            }
        }
    }

    /// <summary>
    /// Extension methods to enable registration of the custom <see cref="IFunctionExecutor"/> implementation generated for the current worker.
    /// </summary>
    public static class FunctionExecutorHostBuilderExtensions
    {
        ///<summary>
        /// Configures an optimized function executor to the invocation pipeline.
        ///</summary>
        public static IHostBuilder ConfigureGeneratedFunctionExecutor(this IHostBuilder builder)
        {
            return builder.ConfigureServices(s => 
            {
                s.AddSingleton<IFunctionExecutor, DirectFunctionExecutor>();
            });
        }
    }
    /// <summary>
    /// Auto startup class to register the custom <see cref="IFunctionExecutor"/> implementation generated for the current worker.
    /// </summary>
    [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Never)]
    public class FunctionExecutorAutoStartup : IAutoConfigureStartup
    {
        /// <summary>
        /// Configures the <see cref="IHostBuilder"/> to use the custom <see cref="IFunctionExecutor"/> implementation generated for the current worker.
        /// </summary>
        /// <param name="hostBuilder">The <see cref="IHostBuilder"/> instance to use for service registration.</param>
        public void Configure(IHostBuilder hostBuilder)
        {
            hostBuilder.ConfigureGeneratedFunctionExecutor();
        }
    }
}