Recently I had to install Oracle 11G R2 on a computer running Windows 10 20H2. Though the software installation completed successfully, I came across a ORA-28000 while creating a new database using DBCA. I was logged in as Domain\Administrator account while creating the database. Immediately remembered our troubles with Windows 2019 server recently, that wouldn’t allow the domain administrator account “Administrator” to change any vitals while logged in! (You may note run in to this situation if you are logged in as another domain administrator, eg: your own user account that is a domain account with admin privileges)
As both Windows 10 & Windows Server OS (2016+) share much of the same code, most of these behaviors are visible on both OS and the thankfully the solutions are the same. If you were having the Oracle installation error ORA-28000 and the situations are matching the above described, please head towards making the following changes. Please note, you must take maximum precautions while changing registry, local security policies etcetera. You must remember, ORA-28000 could arise when Oracle accounts are locked up due different reasons, those you need to take care differently. This post is strictly dealing with the ORA-28000 that arises during the database creation using DBCA.

Run/Execute gpedit.msc

You have to open the node Computer Configuration->Windows Settings->Security Settings->Local Policies->Security Options and configure “User Account Control: Admin Approval Mode for the Built-in Administrator account”. Follow the below image for more details.

Once enabled, you must sign off and log in to bring this mode change in effect. Although this enablement is for the built-in local “Administrator” account, somehow due to the similarities in the account names, Domain administrator account “Administrator” also gets restricted. This could be planned or a bug from Microsoft.
You can use DBCA to delete the database that you were forced to abort during creation & continue creating a database with same name or another now.
Hope this helps few out there!