This error generally occurs when you are trying to trace a user session using the DBMS_SUPPORT package. But this package isn’t installed by default in Oracle. So you have to install it. You can install it using the script dbmssupp.sql
Go to $ORACLE_HOME/rdbms/admin and run dbmssupp.sql to install the package.
cd $ORACLE_HOME/rdbms/admin
SQL> @dbmssupp.sql
Package created.
Package body created.
SQL> exit
Now try the tracing again and it should work.