DBUA error database not in mounted state

 While  upgrading one of my 10.2.0.4 64-bit database to 11.2.0.2 using DBUA it failed  with retrieve db information  and pop up the message

"The Upgrade Assistant failes in bringing up the database XXX. Oracle Home /oracle/OraHome11203 obtained from file /etc/oratab was used to connect to the database. Either the database is not running from Oracle Home /oracle/OraHome11203 or the correct Initialization Parameter file (pfile) was not found"

Then it  ask to locate the pfile.

Actually the database is up and running in 10g ORACLE_HOME: / oracle/OraHome102.

When checked the /etc/oratab entry it was pointing to 10g home only.

Then Error message indicates different scenario here .

 Here environment variable set to:

 LIBPATH=/oracle/OraHome11203/lib:/oracle/OraHome11203/lib32:/usr/lib:/lib

ORACLE_HOME=/oracle/OraHome11203

ORACLE_SID=XXX

PATH=/usr/bin:/etc:/usr/sbin:/usr/ucb:/home/oracle/bin:/usr/bin/X11:/sbin:/oracle/OraHome11203/bin:.

After lots of struggle  we found Welcome_XXX.txt   file in location /oracle/cfgtoollogs/dbua/logs/

$ cat  Welcome_XXX.txt

The presence of this file indicates that the database is opened up with the new Oracle Home binaries.

Here culptit was Welcome_<SID>.txt. After removal of Welcome_<SID>.txt  file  from log dir , everything worked perfectly.