ORA-28001: Oracle expired passwords
Sometimes you forget to check the expiry date for your Oracle users. Then, one day applications that use Oracle database are not working any more, and in the log files you find the ORA-28001 error code, meaning that the database user account is expired and the password should be changed.
You can check your users and their account statuses by using sqlplus, logging in as SYSDBA and checking the information found in DBA_USERS table with the following query:
SQL> SELECT USERNAME,ACCOUNT_STATUS,EXPIRY_DATE FROM DBA_USERS;
Note expired users from the resultset and change their password. There are several ways to do this, but the easiest may be to log in as the expired user by using sqlplus, which will ask you for your old password, and then it will prompt you to enter the new one.