Rider + Azure Functions local runner intermittent failure: Value cannot be null. (Parameter 'provider')

Question

I've been working on an Azure Functions project in Rider and, historically, was able to run local functions just fine.

Then I reformatted my PC, re-installed Rider + dependencies and pulled the functions project from source control again.

Then, local functions executed successfully.

Then, I shut down my computer at the end of the day, and turned it back on the next day.

Then, local functions failed to run:

Found C:\Users\<REDACTED>.csproj. Using for user secrets file configuration.
Error building configuration in an external startup class.
Error building configuration in an external startup class. System.Private.CoreLib: Could not load file or assembly '<REDACTED>, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.
A host error has occurred during startup operation '4f18f32c-7b8a-4e9d-8939-9244c464baae'.
Microsoft.Azure.WebJobs.Script: Error building configuration in an external startup class. System.Private.CoreLib: Could not load file or assembly '<REDACTED>, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.
Value cannot be null. (Parameter 'provider')

I was in a rush so I just used source control to pull down a second copy of that Azure Functions workspace, and that executed just fine!

However, this has now become a repeating pattern. And now that I'm not in much of a rush, I'm trying to figure out what's actually going on because it's quite a waste of time! Here's the pattern:

1. Clone source into new Azure Functions workspace with never-before-used name
2. Local Functions runner works fine
3. I shut down the computer every night
4. Local Functions doesn't work anymore
5. Repeat from step 1

Highlighting the emphasised text in point 1 there: with never-before-used name. Even if I deleted the existing workspace, including from Rider, cloned it again, and opened it anew in Rider, the same failure would still occur. Instead, I have to use a new name for the new workspace.

This suggests to me that there's some sort of caching strangeness going on. I've tried deleting a bunch of different caches to no avail: bin and obj inside the workspace, .azurefunctions and .dotnet inside my user directory.

Running out of ideas now! Any more caches you can think of that I should try deleting? Or other ideas?

In case this is relevant, it's a net6.0 C# Azure Functions project (AzureFunctionsVersion V4) using in-process worker model. There are also other team members running the functions locally, through Rider, without experiencing this error

Answer 1

The error you are getting could be due to the version incompatibility of the packages in your project or configuration issues.

Follow the below steps to resolve the issue:

1. Navigate to your project directory=> delete the bin and obj folders and rebuild the project.
2. This will force Rider to clean and rebuild the entire project from scratch and resolves configuration issues if there is any.
3. Clear cache in Rider, navigate to File=>Invalidate Caches=>Invalidate Restart.

4. Navigate to Tools=>NuGet=> Manage NuGet Packages =>Upgrade dependencies to the latest version.

5. Run the same project in other IDEs like Visual Studio, Visual Studio Code or Azure CLI to check if the issue is with Rider IDE or the project.

• To run the function in Azure CLI, you have to install Azure function core Tools using command.

npm i -g azure-functions-core-tools@4 --unsafe-perm true

If the issue still persists, reinstall Rider and/or the .NET SDK and check again.