I'm getting a runtime error in my functions app but only in Azure, locally everything works fine and neither any issues in my Azure DevOps pipeline.

Question

The error I'm getting is: Microsoft.Azure.WebJobs.Script: Error building configuration in an external startup class. StoringenDWG.Functions: Could not load file or assembly 'Microsoft.Extensions.Configuration.Abstractions, Version=8.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.

I started getting this error when upgrading from .NET 6 to .NET 8 and upgrading all the nuget packages inside my project. I even explicitly added the Microsoft.Extensions.Configuration.Abstractions 8.0.0.0 nuget package to my project file but it doesn't change anything. I've tried a lot of things but nothing seems to work.

I also checked all my dependencies but they all use the 8.0.0.0 version of Microsoft.Extensions.Configuration.Abstractions.

Downgrading the packages isn't a good solution and there must be a reason for it not worrking in Azure but locally it does.

Answer 1

Please ensure you have the following app settings. Most importantly FUNCTIONS_INPROC_NET8_ENABLED

  {
    "name": "FUNCTIONS_EXTENSION_VERSION",
    "value": "~4",
    "slotSetting": false
  },
  {
    "name": "FUNCTIONS_INPROC_NET8_ENABLED",
    "value": "1",
    "slotSetting": false
  },
  {
    "name": "FUNCTIONS_WORKER_RUNTIME",
    "value": "dotnet",
    "slotSetting": false
  }

Reference:
https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-class-library?tabs=v4%2Ccmd#updating-to-target-net-8