I am getting the "server not open" error in SQLPLUS, and the equivalent on Oracle SQL Developer, which says "Oracle Initialization or shutdown in progress".
Fair enough. The fix for this is as follows:
You check to see the status of your database:
select status, database_status from v$instance;
and I see that it is mounted and active. Then I run the following command:
alter database open;
Which generates the following error:
ORA-01157: cannot identify/lock data file 6 - see DBWR trace file ORA-01110: data file 6: 'F:\XXXX_INDEX.DBF'
To resolve this issue, I referred to this resource.
Which is telling me to open the database by running the same
alter database open command as above.
The issue is circular.