> Error is "org.firebirdsql.jdbc.FBSQLException: GDS Exception. index
> unexpectedly deleted" JDBC Driver 1.0.1, FirebirdSQL 1.0.2
> ...
> However I have used this ON DELETE CASCADE with many projects... so
> what is the problem?

This message is generated by server and is not a driver issue. Please
ask in Firebird-Support group.

Best regards,
Roman Rokytskyy