New-AzResourceGroupDeployment fails when deploying a virtual network via ARM template. It seems like the ARM template is iterating through one single IP adress by seeing it's dots ('.') as delimiter:

Errormessage:

New-AzResourceGroupDeployment : 16:00:26 - The deployment 'vm2' failed with error(s). Showing 1 out of 1 error(s).
Status Message: Cannot parse the request. (Code: InvalidRequestFormat)
 - Unexpected character encountered while parsing value: {. Path 'properties.addressSpace.addressPrefixes', line 1, position 133. (Code:InvalidJson)
 - After parsing a value an unexpected character was encountered: :. Path 'properties.addressSpace.addressPrefixes[0]', line 1, position 145. (Code:InvalidJson)
 - After parsing a value an unexpected character was encountered: :. Path 'properties.addressSpace.addressPrefixes[0]', line 1, position 145. (Code:InvalidJson)
 - After parsing a value an unexpected character was encountered: :. Path 'properties.addressSpace.addressPrefixes[0]', line 1, position 145. (Code:InvalidJson)
 - After parsing a value an unexpected character was encountered: :. Path 'properties.addressSpace.addressPrefixes[0]', line 1, position 145. (Code:InvalidJson)
CorrelationId: 5cf0698f-1f96-4adf-a242-312ded6bc9fe
At line:1 char:1
  New-AzResourceGroupDeployment -ResourceGroupName "clientname-rg-vm-01 ...
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      CategoryInfo          : NotSpecified: (:) [New-AzResourceGroupDeployment], Exception
      FullyQualifiedErrorId : Microsoft.Azure.Commands.ResourceManager.Cmdlets.Implementation.NewAzureResourceGroupDeploymentCmdlet

The part of the template file looks like this:

   ..."parameters": {
        "addressPrefixes": {
          "type": "array"
         },
        "subnets": {
          "type": "array"
        }
      },...

        ..."properties": {
               "addressSpace": {
                   "addressPrefixes": "[parameters('addressPrefixes')]"
               },
               "subnets": "[parameters('subnets')]"
           },...

The full template file looks like this:

{
    "$schema": "http://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "environment": {
            "type": "string",
            "metadata": {
                "description": "Omgeving Dev, Tst, Acc, Prd"
            }
        },
        "companyName": {
            "type": "string"
        },
        "resourceType": {
            "type": "string"
        },
        "sequenceNumber": {
            "type": "string"
        },
        "location": {
            "type": "string"
        },
        "networkInterfaceName": {
            "type": "string"
        },
        "enableAcceleratedNetworking": {
            "type": "bool"
        },
        "networkSecurityGroupName": {
            "type": "string"
        },
        "networkSecurityGroupRules": {
            "type": "array"
        },
        "subnetName": {
            "type": "string"
        },
        "virtualNetworkName": {
            "type": "string"
        },
        "addressPrefixes": {
            "type": "array"
        },
        "subnets": {
            "type": "array"
        },
        "publicIpAddressName": {
            "type": "string"
        },
        "publicIpAddressType": {
            "type": "string"
        },
        "publicIpAddressSku": {
            "type": "string"
        },
        "pipDeleteOption": {
            "type": "string"
        },
        "virtualMachineRG": {
            "type": "string"
        },
        "osDiskType": {
            "type": "string"
        },
        "osDiskDeleteOption": {
            "type": "string"
        },
        "virtualMachineSize": {
            "type": "string"
        },
        "nicDeleteOption": {
            "type": "string"
        },
        "adminUsername": {
            "type": "string"
        },
        "adminPassword": {
            "type": "secureString"
        },
        "patchMode": {
            "type": "string"
        },
        "enableHotpatching": {
            "type": "bool"
        },
        "tags": {
            "type": "object"
        }
    },
    "variables": {
        "vmName": "[concat(parameters('companyName'), parameters('resourceType'), parameters('sequenceNumber'), parameters('environment'))]",
        "nsgId": "[resourceId(resourceGroup().name, 'Microsoft.Network/networkSecurityGroups', parameters('networkSecurityGroupName'))]",
        "vnetName": "[parameters('virtualNetworkName')]",
        "vnetId": "[resourceId(resourceGroup().name,'Microsoft.Network/virtualNetworks', parameters('virtualNetworkName'))]",
        "subnetRef": "[concat(variables('vnetId'), '/subnets/', parameters('subnetName'))]"
    },
    "resources": [
        {
            "name": "[parameters('networkInterfaceName')]",
            "type": "Microsoft.Network/networkInterfaces",
            "apiVersion": "2021-03-01",
            "location": "[parameters('location')]",
            "dependsOn": [
                "[concat('Microsoft.Network/networkSecurityGroups/', parameters('networkSecurityGroupName'))]",
                "[concat('Microsoft.Network/virtualNetworks/', parameters('virtualNetworkName'))]",
                "[concat('Microsoft.Network/publicIpAddresses/', parameters('publicIpAddressName'))]"
            ],
            "properties": {
                "ipConfigurations": [
                    {
                        "name": "ipconfig1",
                        "properties": {
                            "subnet": {
                                "id": "[variables('subnetRef')]"
                            },
                            "privateIPAllocationMethod": "Dynamic",
                            "publicIpAddress": {
                                "id": "[resourceId(resourceGroup().name, 'Microsoft.Network/publicIpAddresses', parameters('publicIpAddressName'))]",
                                "properties": {
                                    "deleteOption": "[parameters('pipDeleteOption')]"
                                }
                            }
                        }
                    }
                ],
                "enableAcceleratedNetworking": "[parameters('enableAcceleratedNetworking')]",
                "networkSecurityGroup": {
                    "id": "[variables('nsgId')]"
                }
            },
            "tags": "[parameters('tags')]"
        },
        {
            "name": "[parameters('networkSecurityGroupName')]",
            "type": "Microsoft.Network/networkSecurityGroups",
            "apiVersion": "2019-02-01",
            "location": "[parameters('location')]",
            "properties": {
                "securityRules": "[parameters('networkSecurityGroupRules')]"
            },
            "tags": "[parameters('tags')]"
        },
        {
            "name": "[parameters('virtualNetworkName')]",
            "type": "Microsoft.Network/virtualNetworks",
            "apiVersion": "2020-11-01",
            "location": "[parameters('location')]",
            "properties": {
                "addressSpace": {
                    "addressPrefixes": "[parameters('addressPrefixes')]"
                },
                "subnets": "[parameters('subnets')]"
            },
            "tags": "[parameters('tags')]"
        },
        {
            "name": "[parameters('publicIpAddressName')]",
            "type": "Microsoft.Network/publicIpAddresses",
            "apiVersion": "2019-02-01",
            "location": "[parameters('location')]",
            "properties": {
                "publicIpAllocationMethod": "[parameters('publicIpAddressType')]"
            },
            "sku": {
                "name": "[parameters('publicIpAddressSku')]"
            },
            "tags": "[parameters('tags')]"
        },
        {
            "name": "[variables('vmName')]",
            "type": "Microsoft.Compute/virtualMachines",
            "apiVersion": "2021-07-01",
            "location": "[parameters('location')]",
            "dependsOn": [
                "[concat('Microsoft.Network/networkInterfaces/', parameters('networkInterfaceName'))]"
            ],
            "properties": {
                "hardwareProfile": {
                    "vmSize": "[parameters('virtualMachineSize')]"
                },
                "storageProfile": {
                    "osDisk": {
                        "createOption": "fromImage",
                        "managedDisk": {
                            "storageAccountType": "[parameters('osDiskType')]"
                        },
                        "deleteOption": "[parameters('osDiskDeleteOption')]"
                    },
                    "imageReference": {
                        "publisher": "MicrosoftWindowsServer",
                        "offer": "WindowsServer",
                        "sku": "2019-datacenter-gensecond",
                        "version": "latest"
                    }
                },
                "networkProfile": {
                    "networkInterfaces": [
                        {
                            "id": "[resourceId('Microsoft.Network/networkInterfaces', parameters('networkInterfaceName'))]",
                            "properties": {
                                "deleteOption": "[parameters('nicDeleteOption')]"
                            }
                        }
                    ]
                },
                "osProfile": {
                    "computerName": "[variables('vmName')]",
                    "adminUsername": "[parameters('adminUsername')]",
                    "adminPassword": "[parameters('adminPassword')]",
                    "windowsConfiguration": {
                        "enableAutomaticUpdates": true,
                        "provisionVmAgent": true,
                        "patchSettings": {
                            "enableHotpatching": "[parameters('enableHotpatching')]",
                            "patchMode": "[parameters('patchMode')]"
                        }
                    }
                },
                "licenseType": "Windows_Server"
            },
            "tags": "[parameters('tags')]"
        }
    ],
    "outputs": {
        "adminUsername": {
            "type": "string",
            "value": "[parameters('adminUsername')]"
        }
    }
}

The part of the ARM parameter file looks like this:

   ..."addressPrefixes": {
           "value": [
               "172.50.28.0/22"
           ]
       },
       "subnets": {
           "value": [
               {
                   "name": "default_VM01",
                   "properties": {
                       "addressPrefix": "172.50.28.0/26"
                   }
               }
           ]
       },...

Deployed using New-AzResourceGroupDeployment as well :-

PowerShell version:-

NOTE:- When using az deployment group create need to use cli(az login) and when using New-new-Azresourcegroupdeployment(Connect-AzAccount)

For more information please refer this MICROSOFT DOCUMENTATION| Create Virtual Machine using Template.