ORA-03113 end-of-file on communication channel Error in Oracle

How to Fix ORA-03113: end-of-file on communication channel Error in Oracle Database

This is a generic error and there can be multiple reasons to it. to find the actual reason, you need to consider the alert log and additional infrastructure components as well.

In my case, while doing some maintenance, during DB shutdown, the server was crashed and it kept the database in inconsistency. The background processes got cleared but, the running transactions were still in progress. which was preventing the DB to be up. So after drilling down it was some unarchived logfiles causing this error. I did the following to fix the issue. 

Note: Please do not perform this in PROD without consulting Oracle support, as this might cause some data loss for the uncommitted transactions. 

Steps I followed:

Connect as sysdba:

sqlplus / as sysdba

Startup the database in Mount state:

startup nomount

alter database mount;

Clear the unarchived redo logs:

alter database clear unarchived logfile group 1;

alter database clear unarchived logfile group 2;

alter database clear unarchived logfile group 3;

Keep adding the logfile groups if you have more groups

Now, restart the database:

shutdown immediate

startup

Check the mode on database:

select name, open_mode from v$database;

Hope this helps.

Best Wishes!!