When you are setting up a new Active Directory forest and are trying to add a client to a domain, the following error may come up:
"The domain join cannot be completed because the SID of the domain you attempted to join was identical to the SID of this machine."
This message indicates that the domain controller's SID is identical to your client's. This error can occur when a restored snapshot creates an instance with the same SID.
1. Reset the Windows SID
Note: Rcs is not responsible for data loss or other unexpected updates to the system. Make a backup of the system before performing this action!
We will need to generate a new SID by resetting the current one on the client computer. We can do this by using the sysprep tool, which will reset some elements of your system.
Sysprep is located in C:\Windows\System32\Sysprep\sysprep.exe.
Double-click the .exe file to launch sysprep.
Change the System Cleanup Action to Enter System Out-of-Box Experience (OOBE)
Select Generalize.
Set Shutdown Options to Reboot.
Click "OK".
Step 2: Installation
Please wait while the system is generating its new SID. Check the online console regularly, as you will have to walk through the installation process. When the process is complete, please try joining the domain again.
Resources
See the Microsoft Sysprep documentation for more information.
