Missing dll error from Azure function when updating pipeline - azure

Question

I have an Azure function which triggers when I copy a blob into a container. The function successfully copies the blob into a subfolder for processing but I then want to change the pipeline schedule to trigger the pipeline to run. However, when I try and change the pipeline schedule in code, I get the following error:
Could not load file or assembly 'Microsoft.Threading.Tasks, Version=1.0.12.0, Culture=neutral, ... or one of its dependencies. The system cannot find the file specified.
I've been through the list of nuget packages to remove those that aren't being used and ensure I'm using the latest versions. I've also commented out come of the unnecessary usings in my csx file but I'm still getting the error. If I comment out the pipeline update call, the error disappears and the function runs to the end.
My project.json file looks like this (not that I've included commented out packages to show what other packages I've tried previously):
{
"frameworks": {
"net46": {
"dependencies": {
////"Hyak.Common": "1.1.0",
"Microsoft.Azure.Common": "2.1.0",
"Microsoft.Azure.Common.Dependencies": "1.0.0",
"Microsoft.Azure.Management.DataFactories": "4.11.0",
////"Microsoft.Bcl": "1.1.10",
////"Microsoft.Bcl.Async": "1.0.168",
////"Microsoft.Bcl.Build": "1.0.21",
"Microsoft.IdentityModel.Clients.ActiveDirectory": "3.13.8"
////"Microsoft.Net.Http": "2.2.29"
}
}
}
}
Finally, in the csx file, my usings are as follows (again including commented out lines)
#r "System.Runtime"
#r "System.Threading.Tasks"
#r "Microsoft.WindowsAzure.Storage"
using System;
using System.Net;
using System.Threading.Tasks;
using System.Configuration;
//using Newtonsoft.Json;
using Microsoft.Azure;
//using Microsoft.Azure.Common;
using Microsoft.Azure.Management.DataFactories;
using Microsoft.Azure.Management.DataFactories.Models;
using Microsoft.IdentityModel.Clients.ActiveDirectory;
using Microsoft.WindowsAzure.Storage;
using Microsoft.WindowsAzure.Storage.Blob;
The code to update the pipeline is as follows:
client.Pipelines.CreateOrUpdate(resourceGroupName, dataFactoryName, new PipelineCreateOrUpdateParameters()
{
Pipeline = pl.Pipeline
});
log.Info($"Pipeline rescheduled for {slice}");
If I run this as a console application/web app (which includes several references including Microsoft.Threading.Tasks), the pipeline update works correctly but the same code doesn't work from my Azure function.
Does anyone know what nuget packages/versions or references I might be missing?

Answer 1

It turns out this problem was caused by the project.lock.json file referencing an old version of .Net (i.e. 4.5, rather than 4.6). Updating it to 4.6 resolved the issue.
For completeness, the project.lock.json file now reads as follows:
{
"locked": false,
"version": 2,
"targets": {
".NETFramework,Version=v4.6": {}
},
"libraries": {},
"projectFileDependencyGroups": {
"": [],
".NETFramework,Version=v4.6": []
}
}