How to Solve This Oracle Error ORA-28000: the account is locked

When I try to connect to my Oracle Database, I got this error message:

ORA-28000: the account is locked

The easiest solution for this ORA-28000 issue is simply execute this SQL as SYSDBA from SQL Plus or any other SQL Editor:

alter user <username> account unlock;

Don’t forget to change the bold part <username>.