Deploying VM from VM template always fails at 83% of customize virtual machine step

Question

Hi, having successfully created VM template in SCVMM 2025 (blank local admin password must be set) I am struggling with deploying VM from this template - it always fails at 83% of customize virtual machine step. I put blank local admin password during VM deployment and tried with both workgroup/domain joined options but outcome is the same (OS is Windows Server 2025 Standard).

Am I missing something here?

Answer 1

Root cause is just specialize never firing on a template sealed with a blank admin… if u boot the tmpl once, set a tiny pwd, re‑sysprep /generalize, recapture, and if it still hangs, clear Panther\UnattendGC before retry—this path’s never failed me out there.

Answer 2

The deployment failure is most likely caused by how the template VM was prepared and the local Administrator account/password configuration before Sysprep.

From the documented guidance for creating templates and SAN‑copy–capable templates in VMM:

1. Before creating a template from an existing VM, a new local administrator account must be created on that VM. Using the default built‑in Administrator account causes Sysprep to fail.
2. The VM must not be joined to a domain when Sysprep/generalization is run.
3. The virtual hard disk used for the template must be Sysprepped (generalized) correctly before being added to the library and used as a VM template.

If the template was created with only the built‑in Administrator account (even with a blank password), or the VM was domain‑joined when generalized, Sysprep can fail during the “customize virtual machine” phase, which in VMM typically appears as a deployment failure around the customization step.

To resolve:

1. Rebuild or fix the source VM for the template:
   • Deploy a fresh VM from the Windows Server 2025 media.
   • Create a new local administrator account (do not rely on the built‑in Administrator account).
   • Ensure the VM is in a workgroup (not joined to a domain).
   • Install and configure any required applications.
2. Generalize the VM correctly:
   • Run Sysprep with /generalize and /oobe on the VM so that the associated VHD is properly generalized.
   • Ensure no ISO files are attached to the virtual DVD drive when capturing.
3. Create a new VM template from this correctly prepared VM/VHD in the VMM library.
4. Deploy a VM from the new template, specifying the local admin password and domain/workgroup settings during deployment.

Also note:

• Static IP settings are only available when deploying from a VM template, so if static IPs are being used, ensure they are configured only at deployment time, not baked into the generalized image.
• For security, avoid granting template access to users who do not also have rights to any Run As accounts embedded in the template, as they could extract credentials during deployment.

After recreating the template following these requirements, the “customize virtual machine” step should complete successfully instead of failing at 83%.

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References:

• Add VM templates to the VMM library
• Deploy VMs with rapid provisioning using SAN copy in the VMM fabric