Get an ORA-38818 (illegal reference to editioned object) when trying to create a function-based index on a database with edition based redefinition turned on?
The catch is that your function is in an editioned schema, but indexes are not editionable and cannot reference an editioned object. The work-around is quick and easy:
1) Create a new schema, and do not make it an editioned schema.
2) Create your function in the new schema.
3) Create your function-based index.