Hello #azure, Trying to update our Ubuntu VM from 18.04 to 20.04 by changing the SKU parameter of the ImageReferenceArgs. It failed with the following error:

autorest/azure: Service returned an error. Status=<nil> Code="PropertyChangeNotAllowed" Message="Changing property 'imageReference' is not allowed." Target="imageReference"

Now I changed our code and added this snippet:

, new CustomResourceOptions()
                    {
                        ReplaceOnChanges = new List<string>() { "imageReference" }
                    }

So that new our code looks like this:

DnsForwarder = new VirtualMachine($"{NamePrefix}-vm-dns-forwarder",
                new VirtualMachineArgs
                {
                    HardwareProfile = new HardwareProfileArgs
                    {
                        VmSize = VirtualMachineSizeTypes.Basic_A0
                    },
                    Location = PrimaryLocation,
                    NetworkProfile = new Pulumi.AzureNative.Compute.Inputs.NetworkProfileArgs
                    {
                        NetworkInterfaces =
                        {
                            new NetworkInterfaceReferenceArgs
                            {
                                Id = networkInterface.Id,
                            },
                        },
                    },
                    OsProfile = new OSProfileArgs
                    {
                        AdminPassword = vmAdminPassword.Result,
                        AdminUsername = "hubdnsvm-admin",
                        ComputerName = vmName
                    },
                    ResourceGroupName = args.ResourceGroupName,
                    StorageProfile = new StorageProfileArgs
                    {
                        ImageReference = new ImageReferenceArgs
                        {
                            Offer = "UbuntuServer",
                            Publisher = "Canonical",
                            Sku = "20.04-LTS",
                            Version = "latest",
                        },
                        OsDisk = new OSDiskArgs
                        {
                            Caching = CachingTypes.ReadWrite,
                            CreateOption = DiskCreateOptionTypes.FromImage
                        },
                    },
                    VmName = vmName,
                    Tags = GlobalTags,
                    AvailabilitySet = new Pulumi.AzureNative.Compute.Inputs.SubResourceArgs
                    {
                        Id = availabilitySet.Id
                    },
                }, new CustomResourceOptions()
                    {
                        ReplaceOnChanges = new List<string>() { "imageReference" }
                    }
                    );

Yet, we keep getting the same error message. Any suggestions here on what we do wrong?

My first guess is that you need to provide the full path to that property. In this case, I think it would be

storageProfile.imageReference

I agree with @fast-vr-6049 on both of his recommendations. Re:

deleteBeforeReplace

, the reason you'll need to use that is, it seems you are setting the VM name explicitly instead of using auto-naming, so you can't have two VMs with the same name. But it means for a moment you won't have any VM running until the new is setup after the original one is deleted. Is there a reason you don't want to use Pulumi's auto-naming feature?

Thank you both for your kind advisory. I will try and experiment. There's no specific reason for us not to use the auto-naming feature, we however just need this single low-performance for the purpose of DNS forwarding