I am using Oracle My intention is to create a new database instance.
Here are the steps I have taken,

1. Using DBCA, I created a new database instance, oracle sid = MYORCL0318
2. I created the tablespaces for this instance.

then, I went to Enterprise Manager at http://<hostname>:5501/em

Login = sys
password = xxxxxxx
role = SYSDBA

After I login, I would get an Error like this

java.lang.Exception: Exception in sending Request :: null

Does anyone have any ideas why this is happening and how to fix this? (please let me know if you need additional information.)