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Troubleshoot virtual machine deployment due to detached disks

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Applies to: ✔️ Windows VMs

Symptom

When you're trying to update a virtual machine whose previous data disk detach failed, you might come across this error code.

Code=\"AttachDiskWhileBeingDetached\" 
Message=\"Cannot attach data disk '{disk ID}' to virtual machine '{vmName}' because the disk is currently being detached or the last detach operation failed. Please wait until the disk is completely detached, and then try again or delete/detach the disk explicitly again\”

Cause

This error happens when you try reattaching a data disk whose last detach operation failed. The best way to get out of this state is to detach the failing disk.

Solution 1: Powershell

Step 1: Get the virtual machine and disk details

Azure PowerShell 
PS D:> $vm = Get-AzVM -ResourceGroupName "Example Resource Group" -Name "ERGVM999999" 

PS D:> $vm.StorageProfile.DataDisks 
lun          : 0
name         : f94901ef-75ee-4477-9ad6-1c74da50e7ef
createOption : Attach
caching      : ReadOnly
managedDisk  : @{storageAccountType=Premium_LRS; id=/subscriptions/<subscription ID>/resourceGroups/<Resource Group name>}
diskSizeGB   : 8
toBeDetached : False

Step 2: Set the flag for failing disks to "true"

Get the array index of the failing disk and set the toBeDetached flag for the failing disk (for which AttachDiskWhileBeingDetached error occurred) to "true". This setting implies detaching the disk from the virtual machine. The failing disk name can be found in the errorMessage.

Note

The API version specified for Get and Put calls needs to be 2019-03-01 or greater.

Azure PowerShell 
PS D:> $vm.StorageProfile.DataDisks[0].ToBeDetached = $true

Step 3: Update the virtual machine

Azure PowerShell 
PS D:> Update-AzVM -ResourceGroupName "Example Resource Group" -VM $vm

Solution 2: REST

Step 1: Get the virtual machine payload

rest 
GET https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Compute/virtualMachines/{vmName}?$expand=instanceView&api-version=2019-03-01

Step 2: Set the flag for failing disks to "true"

Set the toBeDetached flag for failing disk to true in the payload returned in Step 1. Please Note: The API version specified for Get and Put calls needs to be 2019-03-01 or greater.

Sample Request Body

JSON 
{
  "properties": {
    "hardwareProfile": {
      "vmSize": "Standard_D2_v2"
    },
    "storageProfile": {
      "imageReference": {
        "sku": "2016-Datacenter",
        "publisher": "MicrosoftWindowsServer",
        "version": "latest",
        "offer": "WindowsServer"
      },
      "osDisk": {
        "caching": "ReadWrite",
        "managedDisk": {
          "storageAccountType": "Standard_LRS"
        },
        "name": "myVMosdisk",
        "createOption": "FromImage"
      },
      "dataDisks": [
        {
          "diskSizeGB": 1023,
          "createOption": "Empty",
     "name": "f94901ef-75ee-4477-9ad6-1c74da50e7ef",
          "lun": 0,
          "toBeDetached": true
        },
        {
          "diskSizeGB": 1023,
          "createOption": "Empty",
          "lun": 1,
          "toBeDetached": false
        }
      ]
    },
    "osProfile": {
      "adminUsername": "{your-username}",
      "computerName": "myVM",
      "adminPassword": "{your-password}"
    },
    "networkProfile": {
      "networkInterfaces": [
        {
          "id": "/subscriptions/{subscription-id}/resourceGroups/myResourceGroup/providers/Microsoft.Network/networkInterfaces/{existing-nic-name}",
          "properties": {
            "primary": true
          }
        }
      ]
    }
  }
}

Alternately you can also remove the failing data disk from the above payload, which is helpful for users using API versions before March 01, 2019.

Step 3: Update the virtual machine

Use the request body payload set in Step 2 and update the virtual machine as follows:

rest 
PATCH https://management.azure.com/subscriptions/{subscriptionId}/resourceGroups/{resourceGroupName}/providers/Microsoft.Compute/virtualMachines/{vmName}?api-version=2019-03-01

Sample Response:

JSON 
{
  "id": "/subscriptions/{subscription-id}/resourceGroups/myResourceGroup/providers/Microsoft.Compute/virtualMachines/myVM",
  "type": "Microsoft.Compute/virtualMachines",
  "properties": {
    "osProfile": {
      "adminUsername": "{your-username}",
      "secrets": [],
      "computerName": "myVM",
      "windowsConfiguration": {
        "provisionVMAgent": true,
        "enableAutomaticUpdates": true
      }
    },
    "networkProfile": {
      "networkInterfaces": [
        {
          "id": "/subscriptions/{subscription-id}/resourceGroups/myResourceGroup/providers/Microsoft.Network/networkInterfaces/nsgExistingNic",
          "properties": {
            "primary": true
          }
        }
      ]
    },
    "storageProfile": {
      "imageReference": {
        "sku": "2016-Datacenter",
        "publisher": "MicrosoftWindowsServer",
        "version": "latest",
        "offer": "WindowsServer"
      },
      "osDisk": {
        "osType": "Windows",
        "caching": "ReadWrite",
        "createOption": "FromImage",
        "name": "myVMosdisk",
        "managedDisk": {
          "storageAccountType": "Standard_LRS"
        }
      },
      "dataDisks": [
        {
          "caching": "None",
          "managedDisk": {
            "storageAccountType": "Standard_LRS"
          },
          "createOption": "Empty",
          "lun": 0,
          "diskSizeGB": 1023,
     "name": "f94901ef-75ee-4477-9ad6-1c74da50e7ef",
          "toBeDetached": true
        },
        {
          "caching": "None",
          "managedDisk": {
            "storageAccountType": "Standard_LRS"
          },
          "createOption": "Empty",
          "lun": 1,
          "diskSizeGB": 1023,
          "toBeDetached": false
        }
      ]
    },
    "vmId": "3906fef9-a1e5-4b83-a8a8-540858b41df0",
    "hardwareProfile": {
      "vmSize": "Standard_D2_v2"
    },
    "provisioningState": "Updating"
  },
  "name": "myVM",
  "location": "westus"
}

Next Steps

If you are having issues connecting to your VM, see Troubleshoot RDP connections to an Azure VM.

For issues with accessing applications running on your VM, see Troubleshoot application connectivity issues on a Windows VM.

Contact us for help

If you have questions or need help, create a support request, or ask Azure community support. You can also submit product feedback to Azure feedback community.