Oracle Error ORA-30026: Undo tablespace ‘string’ has unexpired undo with string(sec) left, Undo_Retention=string(sec)

Oracle Error Message

ORA-30026: Undo tablespace ‘string’ has unexpired undo with string(sec) left, Undo_Retention=string(sec)

Reason for the Error

Tried to drop a tablespace that contains unexpired undo information

Solution

lower setting of UNDO_RETENTION or wait a while before reissue command to drop undo tablespace