oracle error - ORA-00250: archiver not started

ORA-00250:	archiver not started
Cause:	An attempt was made to stop automatic archiving, but the archiver process was not running.
Action:	No action required.

oracle error - ORA-00238: operation would reuse a filename that is part of the database

ORA-00238:	operation would reuse a filename that is part of the database
Cause:	The filename supplied as a parameter to the ALTER DATABASE BACKUP CONTROLFILE command or to cfileSetSnapshotName matches the name of a file that is currently part of the database.
Action:	Retry the operation with a different filename.

ORA-00237:	snapshot operation disallowed: control file newly created
Cause:	An attempt to invoke cfileMakeAndUseSnapshot with a currently mounted control file that was newly created with CREATE CONTROLFILE was made.
Action:	Mount a current control file and retry the operation.