DBUA complains database not in mounted state

"The Upgrade Assistant failes in bringing up the database XXX. Oracle Home /oracle/XXX/11202 obtained from file /etc/oratab was used to connect to the database. Either the database is not running from Oracle Home /oracle/XXX/11202 or the correct Initialization Parameter file (pfile) was not found" Then it asks me to locate the pfile.

My case is similar to http://scn.sap.com/thread/1938507

So cat the Welcome_.txt 

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

/software/orattt/admin/cfgtoollogs/dbua/logs_bak> ls -lrt
total 188
-rw-r----- 1 orattt orattt    102 Oct 21  2010 Welcome_TTTT.txt
-rw-r----- 1 orattt orattt 140879 May 24 16:03 sqls.log
-rw-r----- 1 orattt orattt   2104 May 24 16:07 PreUpgradeResults.html
-rw-r----- 1 orattt orattt  20034 May 24 16:07 trace.log

That is the culprit.

After I rename the directory, everything goes smoothly.