@JohnPaulRaja,C  FinishAssignment, validates, Sets the Task status, completes Assignment and checks for back to back assignments then displays the Review or Perform harness.

You should not have to change anything for that.

The issue you are encountering is likely due to Basic Access Control.  See similar discussion here.

https://docs-previous.pega.com/security/85/verifying-requests-when-using-custom-controls

https://docs-previous.pega.com/additional-update-information-pega-customer-service/pega-customer-service-enhancements-prevent-broken-access-control

We would need you to go  through the usecase and help our support team to understand the issue. You state that when you Click Submit and Trigger Finish Assignment a 403 is returned from server.

-- Do you find any SECU0019 Error in Pega Alert logs and  403 error in network trace?

Can you confirm that this is resolved if you modify  pyBlockUnregisteredRequests as false, everything working as expected?

Have you overridden "pyShowSecureFeatureWarnings" ?   

Please add below snippet in userworkform inside the script tags and let us know if that resolves it:

ClipboardPage actionAPI = ((PegaAPI) tools).getUIEngine().getUIActionPage("finishAssignment"); ((PegaAPI) tools).getUIEngine().getUIAction(actionAPI).register(); actionAPI.removeFromClipboard();