Strange Misleading Error[XML -2018/ AC-10006] while R12 Clone

During the recent Multi Node to Single Node R12 Clone, Encountered an strange error. When doing the database portion of the clone. Below command 'adclonectx.pl' creates the Context file

$ perl adclonectx.pl contextfile=$ORACLE_HOME/appsutil/SOURCE_CONTEXT_FILE.xml template=$ORACLE_HOME/appsutil/template/adxdbctx.tmp pairsfile=$ORACLE_HOME/appsutil/clone/pairsfile.txt initialnode

When running the same command, It dumped the below error,

file:/tmp/tmpCtxClone.xml: XML-20108: (Fatal Error) Start of root element expected.

AC-10006: Exception - org.xml.sax.SAXParseException: file:/tmp/tmpCtxClone.xml: XML-20108: (Fatal Error) Start of root element expected. thrown while creating OAVars object for file: /tmp/tmpCtxClone.xml

The new database context file has been created :
/opt/oracle/product/11.1.0_SID/appsutil/SID_HostName.xml

At first site, I suspected that the issue is with format of the source xml file. Hence compared with the working XML file. Result is clean. Below portion of the error struck me

Thrown while creating OAVars object for file: /tmp//dummy.xml

Cause :

The /tmp is 100% full.

Fix:

Either remove the old files in /tmp directory OR export TEMP=/new/location where there is plenty of free space.