Can anyone help me in fixing the issue (terminating the instance due to error 474) and then Instance terminated by PMON I get these kinds of errors in my oracle logs many times leading to the abnormal shutdown of the oracle instance.

The alert log file contains the logs mentioned below:

Fri Feb 28 22:05:09 2020
Time drift detected. Please check VKTM trace file for more details.
Fri Feb 28 22:05:12 2020
System state dump requested by (instance=1, osid=26083 (PMON)), summary=[abnormal instance termination].
Fri Feb 28 22:05:12 2020
PMON (ospid: 26083): terminating the instance due to error 474
System State dumped to trace file /ora01/app/oracle/diag/rdbms/orcl/orcl/trace/orcl_diag_26097.trc
Fri Feb 28 22:05:14 2020
ORA-1092 : opitsk aborting process
Fri Feb 28 22:05:14 2020
ORA-1092 : opitsk aborting process
Dumping diagnostic data in directory=[cdmp_20200228220512], requested by (instance=1, osid=26083 (PMON)), summary=[abnormal instance termination].
Instance terminated by PMON, pid = 26083
Sat Feb 29 08:40:40 2020
Starting ORACLE instance (normal)
I can't see your trc file to confirm, but it sounds an awful lot like this

https://support.oracle.com/knowledge/Oracle%20Database%20Products/1361872_1.html

Instance Terminated With Error ORA-00474: SMON Process Terminated With Error (Doc ID 1361872.1)
Last updated on JULY 23, 2019


If you login to the MOS system, you'll see the the cause is due to a corrupted INDEX. A diagnostic and remediation script is provided to verify and fix the problem.

Any time you get a message like this or a ORA-600 message, the first place to go is My Oracle Support.