Reslove ORA-08104 : this index object 75350 is being online built or rebuilt

Error

SQL> alter index SCOTT.SYS_C007740 rebuild online tablespace USERS;
alter index SCOTT.SYS_C007740 rebuild online tablespace USERS
*
ERROR at line 1:
ORA-08104: this index object 75350 is being online built or rebuilt

SQL> conn / as sysdba

SQL> select obj#,flags from ind$ where obj#=75350;

OBJ# FLAGS
---------- ----------
75350 2563

SQL> declare
isclean boolean;
begin
isclean :=false;
while isclean=false
loop
isclean :=
DBMS_REPAIR.ONLINE_INDEX_CLEAN(dbms_repair.all_index_id,dbms_repair.lock_wait);
dbms_lock.sleep(10);
end loop;
end;
/

SQL> select obj#,flags from ind$ where obj#=75350;
OBJ# FLAGS
---------- ----------
75350 2051
SQL> alter index SCOTT.SYS_C007740 rebuild online tablespace USERS;