Why my Oracle 12c database seems not to be started?
Your database seems to be up and running, but it was not registered dynamically into the listener.

Try the below:

export ORACLE_HOME=/u01/app/oracle/product/12.1.0/dbhome_1
export PATH=$ORACLE_HOME/bin:$PATH
export ORACLE_SID=info

sqlplus / as sysdba
SQL&gt; show parameter local_listener


Check the value of local_listener. You have 3 options here:


parameter value is empty - in this case, the database registers itself into the listener running on port 1521
parameter value is something like LISTENER_INFO - this is a TNS entry that resolves to the address of the listener. If tnsping LISTENER_INFO resolves to a valid address, the database should be able to register itself to the listener specified by that
parameter value is something like (ADDRESS=(PROTOCOL=TCP)(HOST=hostname)(PORT=1521)). No name resolution is required, database registers itself in the listener.


You most likely have 2. with an unresolvable name, or 3. with and invalid network address.

You can try fixing it with:

alter system set local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))';


Which sets the specified address.

Or:

alter system set local_listener='' scope=memory;
alter system reset local_listener;


Which clears the value of local_listener in memory and spfile, so the database will try registering into a listener running on the default 1521 port.

If this still does not help, you can register your database in the listener statically, by adding the below in listener.ora:

SID_LIST_LISTENER =
 (SID_LIST =
  (SID_DESC =
   (GLOBAL_DBNAME = info.nohoo.biz)
   (ORACLE_HOME = /u01/app/oracle/product/12.1.0/dbhome_1)
   (SID_NAME = info)
  )
 )


After that reload the listener:

lsnrctl reload

Or restart the listener:

lsnrctl stop
lsnrctl start

And try logging in again.