ORA-44787: Service cannot be switched into on Oracle 12c PDB
If you encounter ORA-44787 when switching to PDB using alter session set container , main reason for same can be the unavailability of default PDB service. When a PDB is enabled it does starts its own default PDB service with service name set to the PDB name. Although it is possible to create new service for PDB using DBMS_SERVICE.create_service , it is required to keep the default service up and running as it is used by internal operations. If you have stopped the default service it is the main reason for this particular error. Below is a simple example where stopping of default PDB service leads to ORA-44787 Creating the new service SQL> alter session set container=ORCLPDB; Session altered. SQL> BEGIN DBMS_SERVICE.create_service( service_name => 'new_service', network_name => 'NEW_SERVICE' ); END; 2 3 4 5 6 7 / PL/SQL procedure successfully completed. SQL> exec dbms_service.start_service('new_serv...