Hello A_saeed,
Thank you for posting in Microsoft Community forum.
Yes, you can convert Windows Server 2019 Datacenter to Standard without formatting. You can do this by using the DISM command-line tool. Here are the steps:
- Open an elevated command prompt.
- Type the following command and press Enter: DISM /Online /Set-Edition:ServerStandard /ProductKey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX /AcceptEula
- Replace the "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX" with your valid Windows Server 2019 Standard product key.
- Wait for the process to complete.
- Restart the server.
Note: Before proceeding with the conversion, it is recommended to take a backup of your server and verify that your product key is valid for the Standard edition.
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Haijian Shan