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."
What this indicates, is that the domain controller's SID is identical to your client's. This error can come up on Vultr, as instances with the same SID can be created.
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, the actual program being "sysprep.exe". Double-click the .exe file to launch sysprep. In this screen, you will have to change the System Cleanup Action to "Enter System Out-of-Box Experience (OOBE) and tick "Generalize".
Make sure to put your Shutdown options on "Reboot".
Note: Vultr is in no way responsible for any possible data loss or other unexpected updates to the system. It is highly recommended to make a backup of the system before performing this action!
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.
After this has been done, please try joining the domain again.