Oracle function-based indexes cannot exist on a table when the object is being registered as versioned.
If a table that has an Oracle function-based index is registered as versioned, the following error is encountered:
"Failed to register as versioned. Attribute column not found [ORA-00904: "SYS_NC00019$": invalid identifier (A158)][TOMB.STATES]"
When a table is registered as versioned, ArcGIS detects what indexes are present on the table to create the indexes on the same attributes when the versioned adds table is created.
Once the table has been registered as versioned, the Oracle function-based index can then be created on the versioned table and the table's adds table attribute.