After upgrading or setting up a new on-premises Citrix Virtual Apps and Desktops (CVAD) 2507 site using Windows Server 2025, Virtual Delivery Agents (VDAs) fail to register. Citrix Web Studio reports the following status/suggestion error:

The virtual machine did not complete its start sequence and failed to communicate with the hypervisor.

This indicates a "StuckOnBoot" state where the VDA cannot establish or maintain registration handshakes with the Delivery Controller due to hypervisor communication, boot-sequence, or network layer delays.

To resolve this registration failure on Windows Server 2025, perform the following hypervisor integration checks, network connectivity tests, and VDA service resets.

1. Hypervisor and Integration Checks

• Update Hypervisor Guest Tools: Ensure the latest Hypervisor Integration Services / Guest Tools (e.g., Citrix Hypervisor Tools, VMware Tools, or Nutanix Guest Tools) are installed and updated inside the Windows Server 2025 master image.

• Check Hypervisor Host Status: Verify that the target hypervisor host is not operating in Maintenance Mode and is not experiencing host-level storage or CPU resource exhaustion.

• Inspect Boot State: Log into the VM host console to verify that Windows Server 2025 completes its full boot cycle without hanging on startup scripts, Group Policy processing, or Active Directory authentication delays.

2. Network and VDA Service Actions

• Verify Delivery Controller Port Connectivity:

  Open PowerShell on the affected VDA and test communication to your Delivery Controller (DDC):

  PowerShell

   

  Test-NetConnection -ComputerName <DDC-FQDN> -Port 80
  

  (Note: Use -Port 443 if your site is configured to use SSL/HTTPS communication).

• Restart Citrix Desktop Service:

  Open services.msc on the VDA (or run Restart-Service WorkstationAgent in PowerShell) to restart the Citrix Desktop Service and force a fresh registration handshake.

• Review Event Logs:

  Check the Application and System logs in Windows Event Viewer on both the VDA and Delivery Controller for blocked WCF (Windows Communication Foundation) traffic, DNS resolution failures, or timeout errors.

In a new CVAD 2507 on-premises site, Windows Server 2025 VDAs fail to register with the Delivery Controller.
The registration failure reports that the virtual machine did not complete its start sequence and failed to communicate with the hypervisor.

Review if registration issue still exists - https://support.citrix.com/external/article/CTX136668/how-to-troubleshoot-virtual-delivery-age.html