Oracle Database Discussions

hello to all,

Due to users01.dbf file datablock corruption we need to drop USERS tablespace so we tried below steps
(we have full export dmp file)
1.
sql> ater tablespace users offline;
2.
SQL> drop tablespace users
2 including contents
3 and datafiles
4 cascade constraints;
drop tablespace users
*
ERROR at line 1:
ORA-12919: Can not drop the default permanent tablespace
3.
sql>alter database default tablespace system;
4.
SQL> drop tablespace users
2 including contents
3 and datafiles
4 cascade constraints;
drop tablespace users
*
ERROR at line 1:
ORA-22868: table with LOBs contains segments in different tablespaces

So, how to solve the above error. please give some guidence.

with regards,
Achyot