Configure Virtual Machine UUIDs in VMware Player

Learn how VMware Player assigns virtual machine UUIDs, what happens when you move or copy a VM, and how to preserve its UUID with uuid.action = "keep".

A UUID (Universal Unique Identifier) is an identifier assigned to a specific virtual machine. VMware Player uses the UUID to distinguish one virtual machine from another. The UUID is exposed to the guest operating system through its virtual SMBIOS system information.

SMBIOS, or System Management BIOS information, provides system descriptors that software can query. A guest inventory tool may read the virtual machine's system UUID from SMBIOS even though the guest is running on virtual hardware.

When VMware Player Creates the UUID

VMware Player assigns a virtual machine UUID during the VM's initial power-on. After that, the UUID ordinarily remains unchanged while the VM stays in its existing location and is used normally.

The UUID identifies the virtual machine as a whole. Other components have separate identities:

The guest operating system may generate its own machine ID or product identifier.
Each virtual disk can have its own disk identifier.
A virtual network adapter has a MAC address.
The host computer has physical hardware identifiers that are unrelated to the VM UUID.

Why UUID Persistence Matters

A stable UUID can help system inventory and asset-management software recognize the same virtual machine after routine use. It can also matter to applications that inspect SMBIOS data and to support systems that record a guest-visible hardware identity.

For example, an administrator may record the UUID in an inventory database. If the original VM is moved to a different folder or computer and its UUID is retained, the inventory record can continue to refer to the same virtual machine.

UUID persistence does not make every identifier inside the VM permanent. A move, restore, network reconfiguration, guest operation, or cloning operation can affect other identifiers independently.

What Happens When a VM Is Moved or Copied

When VMware Player detects that a VM's files are being used from a different location, it may ask whether the VM was moved or copied the next time it is powered on.

Moved: Choose this when the files represent the original VM relocated to another path or host. This choice is intended to preserve the VM's existing identity.
Copied: Choose this when the files are a duplicate intended to operate as a separate VM. VMware Player assigns a new UUID.

The question is not merely about file management. It determines whether VMware Player should continue the identity of the existing machine or create a distinct identity for a second machine.

Situation	VMware Player response	UUID result	Recommended choice
Initial VM power-on	Creates the VM identity	A UUID is assigned	Record it if inventory continuity matters
VM remains in the same location	Uses the existing configuration	Normally unchanged	No action required
VM is moved	May ask whether it was moved or copied	Choose moved to retain the existing UUID	Use moved for the original relocated VM
VM is copied	May ask whether it was moved or copied	Choose copied for a newly identified VM	Use copied for an independent test or clone
VMX file includes UUID retention configuration	Uses the configured retention behavior	Current UUID is retained	Use intentionally and avoid identity collisions

Examples: Move Versus Copy

Relocating the original VM

You move a VM from one folder to another because the original storage is full. You are not creating another machine. At the next power-on, select moved. This tells VMware Player to retain the identity of the original VM.

Creating a test copy

You duplicate a production VM to test an update. The duplicate should be an independent machine. Select copied so VMware Player assigns a new UUID. A separate UUID helps inventory systems and applications distinguish the test VM from its source.

Maintaining an inventory record

If an application or inventory system identifies a guest by its SMBIOS system UUID, choosing moved during relocation helps prevent the guest-visible identity from changing. Record the UUID before and after the move when continuity is important.

Preserve the UUID with VMX Configuration

The VMX file is the plain-text VMware virtual machine configuration file. It normally has a .vmx extension and is stored in the VM's folder.

You can configure VMware Player to retain the current UUID during move or copy detection by adding this property:

uuid.action = "keep"

This setting directs VMware Player to keep the current UUID and bypasses the moved-or-copied prompt for that decision.

Safe configuration sequence

Fully power off the VM. Do not edit the VMX file while the VM is running or suspended. A restart is not necessarily the same as a complete power-off.
Locate the VM's folder. If necessary, review virtual machine files to identify the configuration file among the disks, logs, and other files.
Find the VMX file belonging to the VM you intend to change.
Open that VMX file in a plain-text editor.
Add uuid.action = "keep" on its own configuration line. Avoid adding it to a different VMX file or changing unrelated settings.
Save the file and close the editor.
Start the VM in VMware Player.

UUID Retention Versus a New UUID

Goal	Appropriate action	Identity impact	Potential concern
Relocate the original VM	Choose moved, or configure UUID retention	Existing VM identity remains available	Confirm that the files are the original VM
Create an independent clone	Choose copied and allow a new UUID	Clone receives a distinct VM identity	Other guest or hardware identifiers may also need review
Preserve SMBIOS-based asset identity	Record the UUID and use moved or `uuid.action = "keep"`	Guest-visible system UUID remains consistent	Verify that the application is reading the SMBIOS UUID
Run multiple duplicate VMs	Give each independently operated VM a unique UUID	Machines can be distinguished by management tools	Retaining one UUID across copies creates ambiguity

Verify the Guest-Visible UUID

Verification must query the guest's SMBIOS system UUID, not a disk ID, MAC address, operating system machine ID, or product serial value.

Linux guest

On a Linux guest with the appropriate permissions and the dmidecode utility installed, query the system UUID:

sudo dmidecode -s system-uuid

Windows guest

On a Windows guest, PowerShell can query the SMBIOS computer-system product information:

Get-CimInstance Win32_ComputerSystemProduct | Select-Object UUID

Record the value before moving or copying the VM, then run the same check after startup. The result should match when the original VM's UUID was intentionally retained.

Troubleshooting UUID Behavior

VMware Player prompts after relocation

This normally means the VM's location or files changed and no UUID retention property is controlling the decision. Choose moved for the original VM, or copied for a deliberately independent duplicate. If the original UUID must always be retained, power off the VM and add the VMX setting.

The UUID changed unexpectedly

The VM may have been identified as copied during its first startup after a move or duplication. Decide whether the VM is the original relocated machine. For future relocations that require identity continuity, configure uuid.action = "keep" before starting the VM.

The VMX setting has no effect

Check these common causes:

The VM was running, suspended, or not fully powered off when the file was edited.
The property was added to the wrong VMX file.
The line contains invalid syntax or a spelling error.
The file was not saved before the VM was started.

Fully power off the VM, confirm the correct VM folder and VMX file, add the exact property, save it, and start the VM again.

Two VMs show the same system identity

A copied VM may have been configured to preserve the source UUID. For separately operated clones, allow VMware Player to assign a new UUID instead of retaining the source identity.

A guest tool reports a different identifier

The tool may be displaying a disk identifier, MAC address, guest operating system machine ID, or product serial value. Use an SMBIOS-capable inspection tool and confirm that the queried field is the system UUID.

Operational Checklist

Determine whether the files are being moved or copied before powering on the VM.
Record the current SMBIOS system UUID when identity continuity matters.
Choose moved for the original VM relocated to another path or host.
Choose copied for a duplicate that should represent a separate machine.
Power off completely before editing the VMX file.
Use uuid.action = "keep" only when retaining the UUID is intentional.
Verify the result from inside the guest with an SMBIOS-reading tool.
Remember that retaining a UUID and ensuring uniqueness among clones are different operational goals.

For related configuration work, see moving a virtual machine, changing a VM's working directory, and understanding virtual machine files.