Error "Exception of PlanObj.toXML" is returned when trying get an Explain plan for a query which has a variable pointing to CHR(2)
This is due to a bug in SQL Optimizer for Oracle when trying to build the XML for data that contains the #2 character.
WORKAROUND:
Replace the CHR(2) variable with another literal string
STATUS:
Waiting for fix in a future release of SQL Optimizer for Oracle