ORA-04154
cannot create a context handle on behalf of user ID string because it is invalid
Cause
The user_id passed to DBMS_SYS_MLE.create_context_as_user() is either NULL or invalid because it does not map to an existing user.
Action
Provide a valid user id. Compare the user ID passed in the code snippet with those found in the data dictionary. Pluggable databases store information about local users and their corresponding numeric user IDs in DBA_USERS.