After you have updated the image used by a dedicated VDI desktop assignment, you can update the assignment on the Assignments page to update the assigned desktops in the assignment.

For a high-level description of how the agent update capability works in Horizon Cloud for dedicated VDI desktop assignments, see How the Agent Update Feature Works for Dedicated VDI Desktop Assignments.
Important: These steps are for dedicated VDI desktop assignments. These steps do not apply to floating VDI desktop assignments. For information on updating agents in your floating VDI desktop assignments, see Horizon Cloud Pods - Update Agent Software for Images Used by Floating VDI Desktop Assignments.
Caution: While the update agent operation is in progress, you must ensure that you have no other planned activities that might cause any of the assignment's desktop VMs to experience a power change operation. For example, notify your other administrators to avoid manually powering off or on one of these desktop VMs, and ensure that any power management schedules configured in this assignment will not cause the desktops to power on or off while the update agent tasks are running. If a desktop VM experiences a power-change operation while the system is running its agent update tasks on the VM, unexpected results can occur and leave that desktop VM in a state that requires manual recovery.

A best practice is to edit the assignment and remove any configured power management schedules to eliminate the chance a power-change operation will occur while the agent update tasks are running.


  1. Navigate to the Assignments page by clicking Assignments.
    On the Assignments page, a blue dot appears next to the name of any dedicated VDI desktop assignment for which an update applies. If you point at a blue dot, a pop-up box displays indicating the new version of the Horizon Agents Installer available for that assignment.

    The following screenshot illustrates that an agent update is available for the assignment named la24dedsales.

    Screenshot where the Assignments page shows a blue dot on the dedicated VDI desktop assignment, indicating an agent update is available.

    Hold your pointer over that blue dot to see what updates are available.

    Point at the blue dot next to a dedicated VDI desktop assignment to see what agent updates are available.

  2. Select the check box next to the image you want to update.
  3. Click Update Agent.
    The Agent Update wizard appears.
    Screenshot of the Agent Update wizard for updating agents on a dedicated VDI desktop assignment.

  4. In the Software step, select the update version you want to use from the drop-down list.
    Note: For assignments using Microsoft Windows 7 you must select Horizon Agent Installer 20.3.x.
  5. (Required) In the Available VMs to Users field, specify the percentage of desktop VMs in the assignment that you want powered on and available to end users during the update process.
    Important: If you do not need desktops available, type a zero (0). You must specify a value for Available VMs to Users, even when you do not care about having desktop VMs available to users during the update process.
    This value determines how many desktop VMs will be accessible to users over the time the system performs the update on the assignment. This setting is useful for a desktop assignment with a small number of desktops, less than 30 desktops or a few multiples of 30 (like 60 or 90), because it can ensure a higher percentage of a small-sized pool is available as the system goes through updating the desktops. For examples, see How the Agent Update Feature Works for Dedicated VDI Desktop Assignments.

    Setting a higher availability percentage results in an adjustment to the number of desktops in the batch of currently updating VMs. When updating the assignment, the system updates a batch of VMs in parallel. By default, the system uses 30 VMs for each batch until the remaining number of VMs to update is less than 30. At that point, the final batch is for those remaining VMs. Because it takes approximately 30-45 minutes to fully update a VM, even though a set of VMs is getting updated in parallel, that set of update-in-progress VMs is unavailable for that amount of time.

    This option has less effect when the assignment has many desktops, where the system's maximum default 30 VMs per batch is a small percentage of the assignment's total number of desktops.

  6. (Optional) To have the system skip those desktops that have logged-in users (active or disconnected session) or conflicting tasks running, activate the Skip VMs with Logged-in User toggle.
  7. (Optional) Activate the Enable Rollback toggle to have the system create a rollback copy before the agent update is performed and keep that copy for seven days. If the agent update fails on a VM, you then have an opportunity to roll back to the previous agent version for that VM during that seven-day window. For more information, see What to do next at the end of these steps.
    Note: Although the rollback window is set at seven days by default, you can request that VMware change this setting for you.
  8. (Required) For Failure Threshold, enter the number of VMs for which the agent update is allowed to fail before the update process is stopped. This prevents mass failures from occurring.

    The default value is the one you configured in Settings > General Settings

    Note: When the update process stops due to failed VM updates, you might observe a number of failed VMs that is higher than the threshold you set. This can occur for a variety of reasons. For multi-pod assignments, this can occur because the system applies the threshold setting per pod rather than per assignment.
  9. (Optional) To have the system automatically retry any of skipped VMs, activate the Retry Skipped VMs toggle.
  10. (Optional) In the Job Timeout field, specify the time period over which you want the system to continue automatically trying to update the skipped VMs.
    The Job Timeout field sets the number of minutes that the system retries updating the skipped VMs. Every 30 minutes, the system tries to update the skipped VMs until it reaches the end of this time period or until all of the assignment's desktop VMs have been updated.

    You can enter a value that ranges from 120 minutes (2 hours) to 1440 minutes (24 hours). The default value is 720 minutes (12 hours).

  11. If this is a multi-cloud assignment, you can select the pods to update under Select Pods to Update. Pods with manifest version lower than 2632 have a warning icon next to the pod name with hover text saying that Roll Back and Failure Threshold are not supported for that pod.
  12. Click Next.
  13. (Optional) In the Command Line step, add any command-line options that might be relevant for this update on the image.
    The wizard displays a message that indicates whether command-line options are available for the specified update.
  14. Click Submit.


  • A message displays at the top of the page indicating that the update has started.
  • The system updates the agent-related components on the desktop VMs in the dedicated VDI desktop assignment.

You can view the progress of the update task by selecting Monitor > Activity.

What to do next

Go to the Assignments - VDI Desktops page and see if updates were successful. If updates failed for some VMs in an assignment, there is a visual indicator next to the assignment name as shown below.

Assignment with indicator of failed Agent Update

If you have enabled rollback when performing the agent update, you can roll back each failed VM to the previous agent version on the Desktops tab of the assignment detail page. For more information about actions you can perform on the assignment detail page, see Managing Assignments Provisioned By Horizon Cloud Pods in Microsoft Azure.