System.ArgumentNullException: 'Value cannot be null.'

Question

I am relatively new to C# and i have come across this error while working on a project to spin a VM (and support resources in MS Azure).

The code I am using is the one below:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Azure.Management.Compute.Fluent;
using Microsoft.Azure.Management.Compute.Fluent.Models;
using Microsoft.Azure.Management.Fluent;
using Microsoft.Azure.Management.ResourceManager.Fluent;
using Microsoft.Azure.Management.ResourceManager.Fluent.Core;
namespace ConsoleApp1
{
    class Program
    {
        private static void Main(string[] args)
        {

            var credentials = SdkContext.AzureCredentialsFactory.FromFile(Environment.GetEnvironmentVariable("AZURE_AUTH_LOCATION"));
            var azure = Azure
                .Configure()
                .WithLogLevel(HttpLoggingDelegatingHandler.Level.Basic)
                .Authenticate(credentials)
                .WithDefaultSubscription();

Also I have an "azureauth.properties.txt" file i used to set a new Environmental path referenced in the code above as "AZURE_AUTH_LOCATION" .

To set the path i used the simple PS command:

[Environment]::SetEnvironmentVariable("AZURE_AUTH_LOCATION", "C:\MY-PATH\azureauth.properties", "User")

The azureauth.properties file contains simple Tenant/application/key IDs in the format

subscription=<subscription-id>
client=<application-id>
key=<authentication-key>
tenant=<tenant-id>
managementURI=https://management.core.windows.net/
baseURL=https://management.azure.com/
authURL=https://login.windows.net/
graphURL=https://graph.windows.net/

Whenever I am trying to run the project i get an error saying:

System.ArgumentNullException: 'Value cannot be null.'

specifically for the line:

var credentials = SdkContext.AzureCredentialsFactory.FromFile(Environment.GetEnvironmentVariable("AZURE_AUTH_LOCATION"));

Any idea why?

Answer 1

Like luxun said, you have to define the environment variable. For that open the cmd (on windows) and write:

set AZURE_AUTH_LOCATION

this will show the environment variable "AZURE_AUTH_LOCATION". If the result is "Environment variable AZURE_AUTH_LOCATION not defined" or if the path is wrong then write on the cmd:

SET AZURE_AUTH_LOCATION=PathOfTheAzureAuthLocationFile

This should do the trick.

Answer 2

Environment.GetEnvironmentVariable("AZURE_AUTH_LOCATION") must be returning null.

If this is the case you may want to check if that environment variable has actually been defined or whether the file exists.

Define a variable like:

var location = Environment.GetEnvironmentVariable("AZURE_AUTH_LOCATION"); 

When you debug in VS you should be able to inspect the value of location by right clicking on it and clicking quickwatch.

Answer 3

Many thanks for your suggestions. in the end the error was generated by a school-boy mistake in setting the Env Variable in the first place (relative path contained an error I didn't spot earlier).

I was able to run it in the end.

Made a change to define the path in the config file instead too.

thanks