Rename Computer Failing "The hostname is already taken by another device."

[kcyberman17]

Hey there. I am encountering an issue where the rename script is failing to successfully complete the rename properly. The error it throws is "The hostname is already taken by another device." However, no other device exists in AD. I've run into this issue in another environment as well, and was not able to identify what was causing it. From what I can tell, it appears that the DNS name is being updated, but not the computer object. So when it goes to update the computer object, it fails saying a device already exists with that name.

I was able to recreate the issue by running the following command:

PS C:\windows\system32> $name = Get-WmiObject -Class Win32_BIOS | Select-Object -Property SerialNumber
PS C:\windows\system32> $newname = $name.serialnumber
PS C:\windows\system32> Rename-Computer -ComputerName testrename -NewName $newname
Rename-Computer : Fail to rename computer 'TESTRENAME' to '8J6Q494' due to the following exception: The hostname is
already taken by another device.
At line:1 char:1
+ Rename-Computer -ComputerName testrename -NewName $newname
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (TESTRENAME:String) [Rename-Computer], InvalidOperationException
    + FullyQualifiedErrorId : FailToRenameComputer,Microsoft.PowerShell.Commands.RenameComputerCommand

Here are the logs from the RenameComputer script:

Transcript started, output file is C:\ProgramData\Microsoft\RenameComputer\RenameComputer.log

Device is joined to AD domain: REMOVED.local
Scheduled task unregistered.
Renaming computer to 8J6Q494
Rename-Computer : Fail to rename computer 'TESTRENAME' to '8J6Q494' due to the following exception: The hostname is 
already taken by another device.
At C:\Temp\RenameComputer.ps1:161 char:5
+     Rename-Computer -NewName $newName -Force
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (TESTRENAME:String) [Rename-Computer], InvalidOperationException
    + FullyQualifiedErrorId : FailToRenameComputer,Microsoft.PowerShell.Commands.RenameComputerCommand
Rename-Computer : Fail to rename computer 'TESTRENAME' to '8J6Q494' due to the following exception: The hostname is
already taken by another device.
At C:\Temp\RenameComputer.ps1:161 char:5
+     Rename-Computer -NewName $newName -Force
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (TESTRENAME:String) [Rename-Computer], InvalidOperationException
    + FullyQualifiedErrorId : FailToRenameComputer,Microsoft.PowerShell.Commands.RenameComputerCommand

Initiating a restart in 10 minutes

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End time: 20250814224908
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Here is a screenshot of the computer object in AD after the failed rename attempt. After rebooting the computer, the DNS name reverts back to the original computer name.

[TalSeti5]

I'm not positive, but this is a hunch.

The device asset # is used as a quasi hostname with Autopilot / Intune only. And that's what it conflicts with. In Intune, in AP "Devices" list, I think those are effectively "placeholder" device names just for Intune/Entra to use until OOBE generates the "joining host a new name", then registers the official device name. It checks for conflicts everywhere, AD, AAD, etc before it makes the change. Without a template(prefix) - you get DESKTOP-. So it never tries "just asset tag" and this is likely why.
Try that asset tag with any prefix and see if it works. Like X-<assettag#>, to see if this is the problem. Again, a guess as to why this doesn't work.