This record cannot be reserved for update. It has already been reserved by another user

Solution:-

First login with apps user after that find lock on table level.

SQL>  select
   c.owner,
   c.object_name,
   c.object_type,
   b.sid,
   b.serial#,
   b.status,
   b.osuser,
   b.machine
from
   v$locked_object a ,
   v$session b,
   dba_objects c
where
   b.sid = a.session_id
and
   a.object_id = c.object_id;


OWNER                          OBJECT_NAME                                                                                                                   O   BJECT_TYPE                 SID    SERIAL# STATUS   OSUSER                         MACHINE
------------------------------ -------------------------------------------------------------------------------------------------------------------------------   - ------------------- ---------- ---------- -------- ------------------------------ ----------------------------------------------------------------
APPLSYS                        FND_CONCURRENT_REQUESTS                                                                                                       T   ABLE                       768         27 INACTIVE applmgr                   sujeet.oracle.com
PO                             PO_DISTRIBUTIONS_ALL                                                                                                          T   ABLE                       821      11141 ACTIVE   applmgr                   sujeet.oracle.com

18 rows selected.

In my case i am going to kill below lock.

SQL> alter system kill session '821,11141';

System altered.

Issue resolved check and try again..