ORA-19816: WARNING: Files may exist in [string] that are not known to database.
Cause: One of the following events caused this:1. A database crash happened during file creation.2. A backup control file was restored.3. The control file was re-created.4. DB_RECOVERY_FILE_DEST has previously been enabled and then disabled.
Action: Use RMAN command CATALOG RECOVERY AREA to re-catalog any such files. If the file header is corrupted, then delete those files using an OS utility. Do not use messages 19817; it is used for simulating lock failure Do not use messages 19818; it is used for space reclamation before backup Do not use messages 19819; it is used to disable clearing file name