System.IO.FileNotFoundException for Microsoft.DurableTask.Grpc after upgrading Durable Functions to v3.3.1 from v3.0.0 #3232
Description
After upgrading Microsoft.Azure.WebJobs.Extensions.DurableTask from version 3.0.0 to 3.3.1, our Azure Function App fails to execute orchestrator functions due to a missing assembly error:
System.InvalidOperationException: Exception binding parameter 'context'
---> System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.DurableTask.Grpc, Version=1.3.0.0...
Date: Thu, 16 Oct 2025 11:39:31 GMT
Azure Function App (Consumption Plan)
.NET 8
Azure Functions Runtime: v4
DurableTask version: 3.3.1
Function type: In-process
Trigger: Service Bus → Orchestrator
What we've tried:
Removed all references to Microsoft.DurableTask.Grpc from .csproj and shared libraries.
Verified that Microsoft.DurableTask.Grpc.dll is not present in the deployed bin folder (via Kudu).
Cleaned and rebuilt the solution.
Restarted the Function App.
Verified that the host.json does not contain any storageProvider configuration referencing gRPC.
Additional context:
The same code runs fine locally using Azure Functions Core Tools.
The error only occurs in Azure after deployment.
We also observed a related shutdown error in the logs:
NullReferenceException at Microsoft.Azure.WebJobs.Script.Grpc.AspNetCoreGrpcServer.ShutdownAsync()