At the command line; check if the listener is started and running correctly
lsnrctl status
Stop and restart the listener based on listener status
lsnrctl stop lsnrctl start
Use the Enterprise Manager command to check the status of the Database Console
emctl status dbconsole
If you get an error “Environment variable ORACLE_UNQNAME not defined. Please set ORACLE_UNQNAME to database unique name”, please below command to set it accordingly
set ORACLE_UNQNAME=<dbname> e.g: set ORACLE_UNQNAME=orcl
If the dbconsole is already started and active, please restart the dbconsole with below commands
emctl stop dbconsole emctl start dbconsole
Check the status of the console once again
emctl status dbconsole
You should now ideally be able to access the Enterprise Manager