Learn the reason and how to unravel the ORA-01418 error message in Oracle.
When you stumble upon an ORA-01418 error, the following error message will appear:
ORA-01418: specified index does not exist
You have referenced an index that does no longer exist in an ALTER INDEX, DROP INDEX, or VALIDATE INDEX command.
The option(s) to resolve this Oracle error are:
Make positive that your index exists earlier than referencing it in an ALTER INDEX, DROP INDEX, or VALIDATE INDEX command.
You can listing all of the indexes that exist by querying the ALL_INDEXES Oracle machine table:
SELECT * FROM ALL_INDEXES;