I'm trying to drop the tablespace UNDOTBS1 but when I issue the command
drop tablespace UNDOTBS1 including contents and datafiles;
I get the error
ORA-01548: active rollback segment '_SYSSMU9$' found, terminate dropping tablespace
Cause: Tried to drop a tablespace that contains active rollback segment(s)
Action: Shutdown instances that use the active rollback segments in the tablespace and then drop the tablespace
I've tried shutting down the instance from within SQL*Plus but then I get an "ORACLE not available" error when I try to drop the tablespace.