Oracle Message ORA-19813 - cannot have unavailable file string in DB_RECOVERY_FILE_DEST

ERRORcannot have unavailable file string in DB_RECOVERY_FILE_DEST
CAUSEAn attempt was made to change a backup piece or image copy in recovery area to UNAVAILABLE.
ACTIONCorrect and resubmit the RMAN command. Do not use messages 19814; it is used for simulating crash.