Unable to run azure durable orchestration function

I have a simple Azure Functions app, which includes HTTP trigger and a durable orchestration function, which the trigger invokes. This app runs fine when tested locally, but fails when it runs on Azure. The error coming from the orchestrator function is:

07-df83-4d2d-8023-ad4da1eed437, Duration=107ms)Unable to cast object of type 'System.String' to type 'Microsoft.Azure.WebJobs.Extensions.DurableTask.IDurableOrchestrationContext'.

Here is the code for the HTTP trigger:

using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;

public static class DurableHttpStart
{
    [FunctionName("DurableHttpStart")]
    public static async Task<IActionResult> Run(
        [HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req,
        [DurableClient] IDurableOrchestrationClient starter,
        ILogger log)
    {
        // Function input comes from the request content.
        string instanceId = await starter.StartNewAsync("OrchestratorFunction", null);

        log.LogInformation($"Started orchestration with ID = '{instanceId}'.");

        return starter.CreateCheckStatusResponse(req, instanceId);
    }
}

And here is the code for the orchestrator function:

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;
using Microsoft.Extensions.Logging;
using SpreadsheetGear;

public static class OrchestratorFunction
{
    [FunctionName("OrchestratorFunction")]
    public static async Task<List<string>> RunOrchestrator(
        [OrchestrationTrigger] IDurableOrchestrationContext context)
    {
        var finalResult = new List<string>();
        return finalResult;
    }
}

This app is configured as "--dotnet-isolated"

Any ideas how this can be fixed?

As I have mentioned in the comment you are using in-process code in isolated environment. you need to use it in-process environment.

I was also getting same error when I was using similar code in isolated model function app.

My Code: Function1.cs:

using System.Collections.Generic;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.DurableTask;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Logging;

namespace FunctionApp14
{
    public static class Function1
    {
        [FunctionName("Function1")]
        public static async Task<List<string>> RunOrchestrator(
            [OrchestrationTrigger] IDurableOrchestrationContext context)
        {
            var outputs = new List<string>();
            return outputs;
        }

        [FunctionName("Function1_HttpStart")]
        public static async Task<HttpResponseMessage> HttpStart(
            [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestMessage req,
            [DurableClient] IDurableOrchestrationClient starter,
            ILogger log)
        {
            // Function input comes from the request content.
            string instanceId = await starter.StartNewAsync("Function1", null);

            log.LogInformation("Started orchestration with ID = '{instanceId}'.", instanceId);

            return starter.CreateCheckStatusResponse(req, instanceId);
        }
    }
}

FunctionApp14.csproj:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <AzureFunctionsVersion>v4</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.DurableTask" Version="2.12.0" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="4.4.0" />
  </ItemGroup>
  <ItemGroup>
    <None Update="host.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Update="local.settings.json">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
      <CopyToPublishDirectory>Never</CopyToPublishDirectory>
    </None>
  </ItemGroup>
</Project>

When I deployed it to the function in In-process model it worked perfectly fine.

As I mentioned in comment, Isolated model uses different packages as mentioned in this MSDoc.