In the previous post, we have talked about error ORA-01952 when revoking an ungranted system privilege from an user. Similarly, we got error ORA-01927 when revoking an ungranted object privilege from an user.
SQL> revoke select on hr.employees from scott;
revoke select on hr.employees from scott
ERROR at line 1:
ORA-01927: cannot REVOKE privileges you did not grant
ORA-01927 means that the object privilege you want to remove from a user has never been granted to it. That's why the statement failed. You can ignore it if you have known the whole truth.