R12.1.3 : Error while applying patch 18937050

@POS

hello,

R12.1.3 : Error while applying patch 18937050

One of the workers failed with the following error:
FAILED: file POSSPAPM.wft on worker  1

ATTENTION: Please fix the above failed worker(s) so the manager can continue

=======================

Log file is showing :

/u01/app/oracle/tst/apps/apps_st/appl/fnd/12.0.0/bin/WFLOAD &ui_apps 0 Y UPGRADE @POS:patch/115/import/US/POSSPAPM.wft
Log filename : /u01/app/oracle/tst/apps/apps_st/appl/admin/TST/log/l2431152.req


Report filename : /u01/app/oracle/tst/apps/apps_st/appl/admin/TST/out/o2431152.out
Oracle Workflow Definition Loader 2.6.4.0.

Access level: 20, Mode: UPGRADE
  ITEM_TYPE 'WFSTD' is protected, no changes were saved.