Error on Peoplesoft Login page: Invalid User Id or Password.

Case1: Only one user is unable to login

            User account has been locked.

Case2: No one is able to login.

           Password of PS user was locked or changed. If it was locked, unlock it from the back end.

UPDATE PSOPRDEFN SET ACCTLOCK=0 WHERE OPRID='PS';

If the password is changed, change the password from back end and change it in application server and process scheduler server and bounce them.