SAPUSER or connect error rc=99 oerr=12537 error during upgrade

SAPUSER or connect error rc=99 oerr=12537 error during upgrade.

Solution:

check oracle for sessions and process parameters

If the number of processes and sessions is low, make sure that you increase them before you start the upgrade process.

You can calculate the value for the processes and sessions as follows:

processes = 110 + 10 * OsCpuNum;
sessions = 2 * processes;

where OsCpuNum are the numbers of the CPU.

Solution:
To increase the number of processes and sessions, proceed as follows:

1. Log in as orasid user to the UNIX system or sidadm user to the Windows system.

2. Change the values of the processes and/or sessions using sqlplus as follows:

sqlplus /nolog
connect / as sysdba
alter system set processes = "No of process" scope = spfile
alter system set sessions = "No of sessions" scope = spfile

3. Restart the database.

These parameters are not changeable online.

sqlplus /nolog
connect / as sysdba
shutdown immediate
startup