How to solve SP2-0618: Cannot find the Session Identifier. Check PLUSTRACE role is enabled

Logged in as the user owning the objects, you are getting the following error when trying to use the autotrace feature:

SP2-0618: Cannot find the Session Identifier.  Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report

Solution: run the necessary scripts first:

conn / as sysdba
@$ORACLE_HOME/sqlplus/admin/plustrce.sql
grant plustrace to scott;

conn scott/password

@$ORACLE_HOME/rdbms/admin/utlxplan.sql
exit

After this is done, the errors should no longer appear.