oracle errors and how to resolve them

 fix for ORA-03113 end-of-file on communication channel:-

1. SQLPLUS / AS SYSDBA

2. startup mount;

SQL> alter database clear unarchived logfile group 1;

Database altered.

SQL> alter database clear unarchived logfile group 2;

Database altered.

SQL> alter database clear unarchived logfile group 3;

SQL> shut immediate;

SQL> startup ;