ORA-02437 cannot validate

Cause :- This error occur when tries to create a unique index for the unique or primary key index but failed to create unique index.

Solution :-
1. Create an unique index on field.
2. Create NOVALIDATE Primary key.
3. Enable NOVALIDATE Primary Key.
 
CREATE INDEX IND_SY_MENU_USER ON SY_MENU_USER(USER_CODE, CHAILD_ID)

ALTER TABLE SY_MENU_USER
ADD CONSTRAINT PK_SY_MENU_USER_COMP PRIMARY KEY(USER_CODE, CHAILD_ID) NOVALIDATE ;

ALTER TABLE SY_MENU_USER ENABLE NOVALIDATE PRIMARY KEY