i want when user reject record in approval process change field to rejected but it should also show a screen input field before rejecting the record that enter rejection reason which is avalable on that record

Hey Mohit, 

Classic Approval Process's standard Reject button can't launch a screen flow, it only has a plain Comments text box, no way to force a required field or picklist before rejecting. 

The real fix is to move this to a Flow Approval Process instead of Classic Approval Process, that's what Salesforce built specifically for this use case. With Flow Approval Processes, you build the approve/reject screen yourself: 

- Create a Screen Flow with a radio button (Approve/Reject) 

- Use a Decision element, when Reject is selected, show a Rejection_Reason picklist as a required field on that same screen 

- Use the "Resolve Approval Request" flow action (or Update Records if you're setting the field directly) to set Application_Status__c = Rejected and Rejection_Reason__c from what the user entered 

- This entire screen replaces the standard Approve/Reject buttons, so your rejection reason requirement is enforced right there in the flow, no separate popup needed 

If you're on Classic Approval Process and don't want to migrate, there's no native way to inject a screen flow into the Reject button, that part's a real platform limitation. Migrating to Flow Approval Process is the supported path here, not a workaround. 

Reference: