2810819 - Failed oracle upgrade from 11g to 12c

While upgrading Oracle database from 11g to 12c, DBUA stopped in the phase of post upgrade tasks.sql script and terminated itself.  It was not  possible to restart the DBUAtool after that as it selected the new database and give the error that this database can not be upgraded because it is already running on version 12c.

When trying to connect the database using SQL after checking all environment variables and directories which are pointed to the new database the following issue is seen:

SQL> sqlplus / as sysdba;

SQL*Plus: Release 12.2.0.1.0 Production on Fri Jun 14 20:12:11 2019 Copyright (c) 1982, 2018, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup;

ORACLE instance started.

Total System Global Area 1526726656 bytes

Fixed Size                  8747400 bytes

Variable Size             855639672 bytes

Database Buffers          654311424 bytes

Redo Buffers                8028160 bytes

Database mounted.

ORA-00603: ORACLE server session terminated by fatal error

ORA-01092: ORACLE instance terminated. Disconnection forced

ORA-00704: bootstrap process failure

ORA-00604: error occurred at recursive SQL level 1

ORA-00904: "ACDRROWTSINTCOL#": invalid identifier Process ID: 7648 Session ID: 363 Serial number: 15428

Restarting the Oracle server and even the physical server to clean up the shared memory and to close any opened sessions in the background did not change the problem.  The files sqlnet.ora, tnsnames.ora, listener.ora are all pointing to the new directory and locations.

Oracle 11g (11.2.0.3 or 11.2.0.4)

Oracle 12c (12.1.0.2 or 12.2.0.1)

ORA-00904 ACDRROWTSINTCOL# invalid identifier upgrade , KBA , BC-DB-ORA , Oracle , Problem